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Jul 22

Alien Swarm: Reactive Drop Hotfix - July 22, 2025

Alien Swarm: Reactive Drop - Ben Lubar

Added rd_lobby_query_servers convar (default 0 until the problem with the Steam API is fixed) to disable server list queries, which are currently not being properly filtered to just Alien Swarm: Reactive Drop servers by the Steamworks API.
- Note: This means that HoIAF servers are not labelled in-game currently. Progress is still tracked, and HoIAF servers can be found via the Steam Client "Game Servers" list or a website that has a server list, such as https://serverlist.reactivedrop.com/server-list, neither of which appear to be affected by the filtering issue.
Reduced the performance impact of the Steam Workshop download progress widget.

Apr 19

Alien Swarm: Reactive Drop's 8th Birthday

Alien Swarm: Reactive Drop - Ben Lubar

It's that time of the year again. The anniversary of Alien Swarm: Reactive Drop's Steam release.

As always, Alien Swarm: Reactive Drop is only possible due to contributions from community volunteers in the form of donations, code, translations, and game content.

Also as always, there's a double experience bonus going on all throughout this week in-game, and if you look hard enough, you might be able to find some cake.

Mapping Competition 2025

This year's theme is "Residential, Commercial, Industrial". Tag campaigns, missions, or challenges with RCI2025 on the Steam Workshop to enter. Competition entry deadline is August 1st, 2025.

There are a lot of missions in Alien Swarm: Reactive Drop, both in official campaigns and workshop content, that take place around infrastructure like highways, sewers, train stations, or power plants, or in hidden or remote laboratories and military installations. There aren't a lot of missions that take place where people lived and worked prior to the Swarm attack.

Let's change that. This year, your task is to make a short campaign, a mission (standalone, endless, or deathmatch), or a challenge that represents a place that feels "lived in". If you need help getting started, head on over to the Modding / Mapping Help and Tips forum.

Apr 19

AS:RD Update - April 20, 2025 "Received"

Alien Swarm: Reactive Drop - Ben Lubar

It wouldn't be an Alien Swarm: Reactive Drop anniversary update without a shipload of fixes!

Missions

Jacob's Rest: Landing Bay: A crate in the welding tutorial room no longer allows bullets and grenades to pass through.
Jacob's Rest: Deima Surface Bridge: The Bloodhound no longer does friendly fire damage.
Jacob's Rest: Deima Surface Bridge: Moved the forklift and box on the bridge slightly so they are no longer hovering in the air.
Jacob's Rest: Sewer Junction B5: Extended the escape area to include the southeast corner of the breach.
Jacob's Rest: Timor Station: The Bloodhound no longer does friendly fire damage.
Jacob's Rest: Timor Station: Fixed parasites walking on air at the final hack if a small bridge wasn't extended.
Jacob's Rest: Timor Station: Fixed tech requirement staying active during data download.
Jacob's Rest: Timor Station: Removed the delay for opening doors after power activation.
Area 9800: Wastelands: Fixed marines being able to be thrown upwards into a deadly fall by shieldbugs during the final gauntlet.
Area 9800: Wastelands: Fixed tech requirement staying active during data download.
Operation Cleansweep: Storage Facility: Some barrels are no longer marked as debris and can be used for cover.
Operation Cleansweep: Landing Bay 7: Cleaned up invisible walls in the final area.
Operation Cleansweep: Landing Bay 7: Added lights and instructor hints to make it clearer where the escape area is.
Operation Cleansweep: Landing Bay 7: Fixed tech requirement staying active during data download.
Research 7: Transport Facility: Fixed walls turning invisible at certain camera rotations.
Research 7: Jericho Mines: Fixed an invisible hole the floor near the laser.
Tears for Tarnor: Insertion Point: Moved satelite dishes slightly to avoid them obstructing the view while inside the outpost.
Tears for Tarnor: Abandoned Maintenance Tunnels: Replaced the broken window laser bypass route with stairs.
Tears for Tarnor: Abandoned Maintenance Tunnels: The laser is now red because red lasers are more scary-looking. (Please stop walking into the laser.)
Tears for Tarnor: Abandoned Maintenance Tunnels: Added CAUTION signs surrounding the path that goes through the laser.
Tears for Tarnor: Spaceport: Fixed tech requirement staying active during data download.
Tilarus-5: Arctic Infiltration: Fixed tech requirement staying active during data download.
Tilarus-5: Yanaurus Mine: Expanded the area that counts as being on the elevator for starting it moving.
Tilarus-5: Forgotten Factory: The Bloodhound no longer does friendly fire damage.
Tilarus-5: Forgotten Factory: Fixed the elevator being blocked by dropped weapons.
Tilarus-5: Communication Center: Fixed tech requirement staying active during data download.
Lana's Escape: Lana's Complex: Extended escape area to be more intuitive.
Paranoia: Unexpected Encounter: Fixed tech requirement staying active during data download.
Nam Humanum: Platform XVII: Fixed platform being blocked from moving when marines stood in certain locations.
Nam Humanum: Platform XVII: Fixed bot marines being left behind in some cases.
BioGen Corporation: Operation X5: Fixed tech requirement staying active during data download.
Reduction: Operation Sandstorm: Fixed strange terrain rendering near north-west objective.
Reduction: Operation Sandstorm: The entry ship can no longer be destroyed by marines.
Bunker: Removed a misplaced kill plane above the starting and ending rooms.
Reversed Cargo Elevator: Expanded the area that counts as being on the elevator for starting it moving.

Weapons

M42 Vindicator: Made grenade visual effects more resilient against packet loss.
Model 35 Pump-action Shotgun: Fixed reloading automatically when firing a double blast even if automatic reload was disabled.
M868 Flamer Unit: Fixed reloading automatically while shooting extinguisher even if automatic reload was disabled.
M868 Flamer Unit: Fixed the flamer appearing to fire while empty when automatic reload was disabled if there was only 1 unit of flamer fuel remaining.

Models

Forklift: Updated the physics mesh.
Containerload: Added a physics mesh for cargo containers.

Misc

Fixed jittery movement of spotlight glows.
Added cl_showspectators convar.
Added Die() vscript function to inhabitable NPCs.
Added "friendlyfire" property to sentry tops in Hammer.
Removed and reverted the rd_drone_flinch_resets_attack convar.
Added support for the "Back" command on the settings screen for custom UI reskins.

Infection Deathmatch

Fixed scripts breaking upon new round start.
If you are still experiencing issues, please contact ModdedMarionette.

The IAF needs you!

Alien Swarm: Reactive Drop will always be free, but that doesn't mean it doesn't take a lot of work from a lot of talented volunteers to make. If you can, consider making content for the Steam Workshop, reporting bugs, proposing code improvements, translating the game into your language, or sending a dollar to one of the people who made Alien Swarm: Reactive Drop possible. The IAF thanks you for your continued service, Commander.

Dec 31, 2024

AS:RD Update - January 1, 2025 "Scavenger"

Alien Swarm: Reactive Drop - Ben Lubar

It's 2025, and to start the year off we have a pile of community-requested fixes!

Commanders searching for anomalous materials together may find them quicker.
Added convar rd_chat_item_messages to opt out of messages about players obtaining items such as medals and crafting materials. (Suggested by Ax-now)
Fixed commanders who opted into phase 2 but not phase 1 not being able to see certain informational UI elements in menus.
Jacob's Rest: Deima Surface Bridge: Removed marine hints from an out of bounds area. (Reported by typical russian)
Jacob's Rest: Deima Surface Bridge: Extended triggers on the bridge upwards to avoid players being able to accidentally jump jet over them and have infinite spawners never turn off. (Reported by WTF-8)
Jacob's Rest: Deima Surface Bridge: Added an incorporeal ceiling in first and third person over the building where the first hack occurs.
Jacob's Rest: Rydberg Reactor: Fixed missing rangers during the final holdout. (Reported by WTF-8)
Jacob's Rest: Rydberg Reactor: Fixed a spot where marines could jump jet to their death. (Reported by WTF-8)
Jacob's Rest: Rydberg Reactor: Extended escape area to the entire area beyond the last door. (Reported by typical russian)
Reduction: Silent Station: Fixed missing aliens during the final holdout. (Reported by WTF-8)
Reduction: Fallen City: Fixed a potential soft lock when skipping the skyscraper. (Reported by WTF-8)
Reduction: Stowaway: Fixed the door opening sequence at the start of the mission being delayed if the door was not damaged. (Reported by WTF-8)
Reduction: Inevitable Escalation: Fixed a spot where marines could die while watching the final cutscene. (Reported by WTF-8)
Area9800: Landing Zone: Fixed the exit being accessible via jump jets before the door is open. (Reported by WTF-8)
Area9800: Power Plant's Cooling Pump: Fixed the escape area not being treated as an escape area until all other objectives were completed.
Lana's Escape: Lana's Vents: Fixed marine bots taking an unexpectedly long path. (Reported by WTF-8)
Lana's Escape: Lana's Maintenance: Fixed an invisible wall with grenade collision at the northeast end of the map when the camera is rotated. (Reported by WTF-8)
Operation Cleansweep: U.S.C. Medusa: Added protection against the doors of the main elevator getting stuck.
BioGen Corporation: BioGen Labs: Fixed tech marine requirement not being properly removed after the last hack. (Reported by WTF-8)
Research 7: Jericho Mines: Fixed hitbox for lava being too large. (Reported by WTF-8)
Tilarus-5: Yanaurus Mine: Fixed an invisible wall with grenade collision. (Reported by WTF-8)
Tilarus-5: Forgotten Factory: Fixed a broken door suggesting players weld it. (Reported by WTF-8)
Tilarus-5: SynTek Hospital: Fixed a broken door suggesting players weld it. (Reported by WTF-8)

Nov 30, 2024

AS:RD Update - December 1, 2024 "Invitation"

Alien Swarm: Reactive Drop - Ben Lubar

It's December, and that means it's time for the monthly update!

There's a message here, addressed to you.
M868 Flamer Unit: Adjusted friendly fire damage and duration on normal friendly fire difficulty. (Thanks, ModdedMarionette).
- Hardcore friendly fire is unchanged.
- Friendly fire with a flamethrower now once again ignites immediately.
- Damage now scales up linearly rather than slower at the start and faster at the end of the burn duration.
- Afterburn duration is decreased by the amount of time since the previous friendly fire incident, minus two seconds.
- Maximum afterburn duration is 100%, and minimum is 18.75%.
- This means the minimum burn time for friendly fire with default game rules is: Easy: 1.125s, Normal: 1.5s, Hard: 2.25s, Insane and Brutal: a little over 2.8s.
- Afterburn from friendly fire is now counted as friendly fire in mission statistics.
Chainsaw: Lag compensation is now disabled by default. (Suggested by WTF-8).
Bot marines will use guns rather than melee when they have been damaged by multiple enemies in quick succession. (Suggested by WTF-8).
Sentries that have ammo remaining now revert to box form when they are destroyed rather than being completely lost.
Added several functions to the Director VScript interface for querying the list of NPC types. See the Valve Developer Community wiki for details. (Suggested by ModdedMarionette).
Entities that push such as doors and trains now deal damage to non-boss aliens they are unable to push.
Fixed a texture reference count issue with the LanguagePreference material proxy. (Reported by mutezero).
Marine reservation time is now 2 seconds after an instant restart rather than the 30 seconds that a full map load provides. (Suggested by WTF-8).
Added a new main menu background themed after the Nam Humanum campaign. (Thanks, mfz).

The IAF needs you!

Oct 31, 2024

AS:RD Update - November 1, 2024 "Tune-Up"

Alien Swarm: Reactive Drop - Ben Lubar

22A7-Z Prototype Assault Rifle: Removed damage falloff from alternate fire. Now does 1 damage regardless of distance for any target it hits rather than some fraction of a point of damage.
IAF Incendiary Sentry Gun: Fixed a 2010 era bug causing this sentry to consume 2.5 ammo per shot.
Fire Extinguisher: This item can now always be picked up both in the temporary slot or in a normal weapon slot, rather than being decided per map location. Change rd_fire_extinguisher_force_temporary if this breaks your challenge.
Mining Laser: Fixed a visual issue where the beam would appear to follow the player's aim direction when the laser was being fired by a bot added by that player.
Increased the default size of the fast reload indicator (rd_fast_reload_under_marine_scale) from 1x to 3.5x.
Guns will now consistently start their automatic reload immediately after becoming empty rather than waiting for the primary fire button to be released or the shot interval timer to complete.
Lowered the damage threshold where Harvesters will not spawn Xenomites on death from 135 damage to 125 damage. The requirements that the damage dealt is more than double the Harvester's remaining health and that the damage type was blast remain the same. This means direct hits from rifle grenades should more consistently be able to cleanly kill wounded Harvesters.
Fixed the lobby creation max players dropdown resetting to 4 when the menu is reloaded after changing a setting that moves to a different screen.

The IAF needs you!

Aug 31, 2024

AS:RD Update - September 1, 2024 "Time's Down"

Alien Swarm: Reactive Drop - Ben Lubar

Mapping Competition 2024 Winner

Downed Station by legomanas

Changes in this update

Removed the cl_interp convar. The game will now act as if it was set to 0.
Improved the error message that is shown when attempting to connect to a server that hasn't updated yet.
Fixed a particle related crash due to the "emit noise" operator being broken in this engine build.
Fixed a possible crash when navigating the controls menu using a keyboard.
The sound for a marine being burned but not ignited now plays for other players as well.
Slightly increased how lenient the friendly fire ignite timing is when hardcore friendly fire is disabled.
Fixed a case where TF2 workshop item icons could appear in the challenge selection screen for manually installed challenges.
Added an AddTime input for countdown objectives.
Fixed a crash when standing near a strange weapon dropped by a disconnected player.
Added support for guns having a separate laserpointer attachment from their muzzle attachment.
Moved camera-related convars to the server to make them available to challenges.
Fixed some small text being displayed in Times New Roman on Linux.

The IAF needs you!

Jul 31, 2024

Alien Swarm: Reactive Drop Update - August 1, 2024

Alien Swarm: Reactive Drop - Ben Lubar

This month's update is mainly related to weapon quality of life improvements.

X-33 Damage Amplifier: Fixed a carried beacon not reliably connecting to the gun of the marine carrying it.
X-33 Damage Amplifier: rd_buff_grenade_attach_sw_auto can now be set to 2 to restore the old behavior of allowing a special weapons marine to carry multiple damage amplifiers. You can still only pick one up from the ground if you are not already carrying one. Persistent damage bonuses still do not stack, so this is only useful if you want to bridge the gap between two damage amplifier durations by slightly overlapping them.
X-33 Damage Amplifier and IAF Heal Beacon: Added an extra ring to the animation of the beacon to show remaining duration. Custom particle effects can use this information from the control point 1 y coordinate, which scales from 0 on a freshly deployed beacon to 1 when the beacon expires.
v45 Electric Charged Armor: Added a convar rd_electrified_armor_fx which can be turned off to disable the electrical effect in case it looks bad on custom models.
TG-05 Gas Grenades, FG-01 Hand Grenades, and CR-18 Freeze Grenades: Added a visual representation of equipped grenades to marines.
TG-05 Gas Grenades, FG-01 Hand Grenades, and grenades from the Grenade Launcher now use separate models for easier modding.
M868 Flamer Unit and M478 Proximity Incendiary Mines: Friendly fire with incendiary weapons now ignites marines immediately on all difficulty settings. Instead, afterburn damage on normal friendly fire takes a few seconds to ramp up to its full damage. This is an experimental change intended to make friendly fire with incendiary weapons more apparent without changing the effective difficulty much and to ease the transition between playing on normal and hardcore friendly fire. As always, we are collecting feedback and will make changes as needed.
Fixed consumable weapons appearing to float in the air for a fraction of a second after being used up.
Fixed a crash related to memory corruption when switching challenges after restarting the mission.

Jul 14, 2024

Alien Swarm: Reactive Drop Update - July 15, 2024

Alien Swarm: Reactive Drop - Ben Lubar

New material shader: RDCharacter

This replaces the VertexLitGeneric shader and the AlienSurfaceFX and NightVisionSelfIllum material proxies for characters in Alien Swarm: Reactive Drop.

For Modders

If your mod does not contain VMT files for characters, you do not need to make any changes.
If your mod's VMT files for characters start with the word "patch", you are likely already using the updated shader.
If your mod's VMT files for characters start with the words "VertexLitGeneric", see below.
If your mod's VMT files for characters start with any other words, you are on your own.
If you do not update your VMT files, your materials will continue to work as they have prior to this update, but the models with those materials will not have access to the new features of this shader.

Updating VertexLitGeneric character materials

Replace "VertexLitGeneric" at the start of the file with "RDCharacter".
Remove any line starting with "$detail". (If you want to use $detail for something else, it is no longer reserved for status effects in the new shader.)
If there is an "AnimatedTexture" proxy for "$detail", remove "AnimatedTexture" and everything from the following { to the next }.
Replace the "AlienSurfaceFX" proxy with "RDCharacter". If your material does not have a Proxies section, instead add Proxies { RDCharacter {} } before the last } in the file.
Remove any references to night vision (for example, the NightVisionSelfIllum proxy, any LessOrEqual proxy connected to it, helper variables like $one, $zero, and $selfIllumTint_dark).

New features in RDCharacter

The $detail variables are no longer used for status effects, meaning they can be used for other purposes.
Night vision no longer uses $selfillum, meaning changes to the $selfillum settings do not alter night vision's effects.
On systems with Shader Model 3.0 support, the fire, ice, and shock status effects no longer cause each other to scroll at different speeds.
The fire status effect now consistently animates on all character types.
Added a "team highlight" border similar to the "Character Highlighting System" added to Warframe in Update 34: Abyss of Dagath.
Any new character shader effects added in the future will not require mandatory VMT changes.
It took 10 hours, 43 minutes, and 26 seconds to compile the 21,900 variants of the new shader.
Note: On systems lacking Shader Model 3.0 support, $detail is disabled when a status effect is active to reduce shader complexity.
Note: On systems lacking Shader Model 3.0 support, $rimlight is disabled when a team highlight is active to reduce shader complexity.

Team Highlights

rd_highlight_active_character, rd_highlight_allies, and rd_highlight_enemies can now be set to show colored borders on characters for easier identification.
rd_highlight_active_character continues to show a border surrounding the marine as it did before in addition to the new border.
rd_highlight_allies_color defaults to a grayish blue, and rd_highlight_enemies_color defaults to a more saturated red.
The highlight ConVars can be set to higher values to highlight more of the character's model. Setting the ConVar to 1 (recommended) highlights the edges of the character's silhouette, and setting it to 2 highlights almost the entire character. Fractional values like 2.5 and 0.8 are also accepted.
Set rd_deathmatch_team_color_highlight to 0 to revert to the previous system of tinting marine models in Team Deathmatch.
This system is intended to decouple the accessibility aspect of many alien reskins from the artistic aspect, making it so players don't need to choose between being able to see the aliens and having the aliens look how they want.
For those familiar with the game's codebase, rd_highlight_ignore_class is also available to exclude specific character types from the team highlights system. For example, rd_highlight_ignore_class 27,40 would omit highlights from drones and marines.

X-33 Damage Amplifier

Added a ConVar to make Special Weapons marines pick up X-33 Damage Amplifiers automatically.

ConVar

rd_buff_grenade_attach_sw_auto (default 0; set to 1 to pick up damage amplifiers automatically.)

This also affects bots added by the player. This setting is stored in config.cfg. Use host_writeconfig to save your changes.

Alien Shadow-Bending

Added convars to give jumping and/or flying aliens vertical shadows like the Half-Life 2 crane to make it easier to tell where they are in 3D space.

ConVars

rd_alien_vertical_shadow_jumping (default 1; set to 1 to give Drones, Parasites, and Xenomites vertical shadows when they are jumping)
rd_alien_vertical_shadow_flying (default 0; set to 1 to give Buzzers vertical shadows)
rd_alien_vertical_shadow_distance (default 4096; the maximum distance above the ground a vertical shadow can be cast from)
asw_alien_shadows being set to 0 now affects Buzzers as well

The three new ConVars are currently not stored in config.cfg. They may be added later, but for now, use autoexec.cfg for these settings.

And more...

Mapper-placed Xenomites (whether placed as asw_parasite_defanged entities or spawned via a spawner) no longer expire after 60 seconds.
Xenomites from a Harvester still expire after 60 seconds of not finding a marine as before.
Fixed npc_cscanner not respecting its "neutral" flag, causing it to be an attack target for bots and aliens in Paranoia: Hostile Places.
Over 100 commanders have signed the contract.
NPCs now cancel their current movement intent when they are frozen. This fixes the "drifting" that some aliens exhibited.
Fixed unexpected jigglebone behavior when a frozen enemy is forced to move (such as by standing on a moving platform).
Fixed marines with CR-18 Freeze Grenades equipped having an extra shadow between their feet.

Jun 30, 2024

Alien Swarm: Reactive Drop Update - July 1, 2024

Alien Swarm: Reactive Drop - Ben Lubar

Commander,

The Office appreciates your hard work on the anomalous materials project. The folks in the lab say they'll be ready for phase 2 soon. We'll let you know when it's ready. You'll know it when you see it.

Oh, and happy wrath month.

Dr. Helvetica Scenario
Ecological Consistency Dept.
Office of Consensus Maintenance

Aliens

Aliens no longer fail to deal damage when melee attacking another alien due to a custom ai_relationship.
Freezing a character now also slows down the simulation of jigglebones. (For example, the antenna or cables on a marine's backpack.)
Drones now flinch based on the stats of the weapon that hurt them, not the marine's current weapon. (For example, switching from a flamer to a PDW while the fire is traveling no longer has a lower chance to cause flinches.)
Frozen aliens no longer restart their current animation when thawing and can no longer move or turn while frozen in some cases.
Boomers can no longer decide to explode while frozen.
Removed shadow from the queen's tentacles.
Melee now deals double damage to frozen enemies. There are also new convars for damage scaling against burning enemies for use by mods.
Enemies can now be over 100% frozen. Thawing is slightly faster for aliens above 100% frozen until they fall below 100%.
Stepping on a parasite or xenomite now deals 1 damage rather than 15.
Fixed xenomites being able to detonate and parasites being able to infest while completely frozen.
Fixed parasites and xenomites not using custom models.

Weapons

Model 35 Pump-action Shotgun: No longer fires after being picked up if dropped or holstered during its alternate fire double blast.
X-33 Damage Amplifier: This item is no longer picked up automatically when deployed by a Special Weapons marine. Instead, a Special Weapons marine can pick up an already-deployed beacon. (For example, Wolfe can pick up a damage amplifier deployed by Bastille, and Wolfe can also deploy a damage amplifier and leave it on the ground.)
Renamed the Special Weapons skill "Autogun Damage" to "Heavy Weapons".
Renamed the Special Weapons skill "Piercing Bullets" to "Stopping Power".
The Stopping Power skill now also increases the chance for a weapon to cause enemies hit by it to flinch.
Fixed two magazines being visually dropped after a reload in singleplayer.
Fixed cases where bots would not have bullet spread.
The laser pointer no longer stops when it reaches a rolling marine.
Weapon-specific ammo boxes now give an amount of ammo based on the gun's magazine size to support challenges that change magazine size.

Modding

Adjusted several UI elements to better support modding.
Reorganized files so that dedicated servers do not download files required only for the client, such as sounds, shaders, textures, and GPU-optimized models.
Moved ASBI, Energy Weapons, First Person, and Third Person to the top of the challenge list. Renamed "Disabled" challenge to "Default Game Rules". These changes are intended to make it easier for new players to understand that challenges are all game rule changes, not just game rule changes that make the game harder.
Fixed main menu experience bar being completely wrong.
Setting rd_player_bots_allowed to 0 now leaves every commander with a maximum of 1 marine rather than 0.
Fixed the IAF Freeze Sentry Gun and the IAF Incendiary Sentry Gun ignoring the PreventFiringUntil function.
Added support for Portal 2 style $localrefract (as used in props_lab/glass_lightcover.mdl).
Fixed some cases where opening the game from the SDK would delete the locally cached version of your inventory.

...

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