A physics-first quadcopter laboratory: 1000Hz modeling, detailed real-world airframes from 2" to 13", a virtual workbench, a built-in flight controller, race tracks, and full flight record & replay — design, tune, and fly real drone builds before you touch hardware.

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Early Access Game

Get instant access and start playing; get involved with this game as it develops.

Note: Games in Early Access are not complete and may or may not change further. If you are not excited to play this game in its current state, then you should wait to see if the game progresses further in development. Learn more

What the developers have to say:

Why Early Access?

“SITL Forge is built by drone pilots for drone pilots, and we'd rather ship it now and shape it together with the community than polish it in isolation. Early Access lets builders, FPV pilots, and flight-controller developers try the simulator against real hardware setups, tell us what's missing, and influence which platforms and features we prioritize next.”

Approximately how long will this game be in Early Access?

“We plan to remain in Early Access for approximately 6–12 months. The exact length depends on how quickly we can act on community feedback, expand the parts library, and ship the next flight-controller integrations.”

How is the full version planned to differ from the Early Access version?

“During Early Access we plan to grow the simulator along several axes:
• Additional flight-controller integrations as DLC — ArduPilot is planned alongside the existing Betaflight and iNAV support.
• A larger parts library: more frames, motors, propellers, batteries, and ESCs, with bench-validated specifications.
• Additional environments and test scenarios.
• Continued refinement of the VMG motor/propeller physics model based on real bench-test data.
• Quality-of-life improvements driven by community requests.

These are our intentions, not promises — final scope will depend on how Early Access unfolds.”

What is the current state of the Early Access version?

“SITL Forge is fully playable today and includes:
• A built-in SIM flight controller (ACRO / ANGLE / HORIZON) for standalone simulation.
• Betaflight and iNAV DLC integrations for running real firmware in software-in-the-loop — Betaflight for flight tuning, iNAV for GPS navigation and waypoint missions.
• 1000 Hz Jolt physics with a power-balance VMG motor/propeller model.
• A drone workbench with part assembly, real-time thrust and current predictions, and joystick support.
• Detailed real-world airframes from a 2" micro to 13" heavy carriers.
• Race tracks with lap timing, practice and 3-lap race modes.
• Flight recording and full 3D replay.

The current build ships with one environment and a growing library of parts and race tracks, and may contain bugs and rough edges. We will be expanding content and fixing issues throughout Early Access.”

Will the game be priced differently during and after Early Access?

“We plan to gradually raise the price as the simulator grows — additional flight-controller integrations, an expanded parts library, and new environments will be reflected in the price during and after Early Access. Customers who purchase during Early Access keep their copy and do not pay the difference later.”

How are you planning on involving the Community in your development process?

“We see Early Access as a working dialogue with our players. We plan to:
• Use the Steam Community Hub for feature requests, polls on what to build next, and bug reports.
• Publish regular changelogs that credit community-driven improvements.
• Engage directly with flight-controller developers and FPV builders who test real firmware against the simulator — their setups are the toughest test of physics fidelity.
• Share experimental builds for community review when meaningful changes land.”
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Download SITL Forge - FPV Laboratory Demo

Buy SITL Forge - FPV Laboratory

Buy SITL Forge - Betaflight collection BUNDLE (?)

Includes 2 items: SITL Forge - FPV Laboratory, SITL Forge – External FC: Betaflight

0% off. $17.49 normally, discounted to $17.49

Buy SITL Forge - iNAV collection

Includes 2 items: SITL Forge - FPV Laboratory, SITL Forge – External FC: iNAV

0% off. $17.49 normally, discounted to $17.49
 

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About This Game

SITL Forge is a physics-first FPV simulator. Motors, props and batteries are fitted to real bench data, physics runs at 1000 Hz, and every airframe is a real-world design — from a 2" micro to a 13" cinelifter. Fly it, race it, build it — or plug in real Betaflight and iNAV firmware.

Fly

  • Built-in Betaflight-style flight controller: ACRO, ANGLE, HORIZON, live PID and rate tuning
  • Race tracks with real-size gates and timed laps — practice or a 3-lap race
  • FPV camera with real lens distortion; any joystick or USB RC transmitter

Build

  • Swap frames, motors, props and packs in the workbench — weight, thrust, current and flight time recompute instantly
  • Detailed real-world airframes, 2" to 13", down to screws, cables and battery straps

Real physics

  • Motor losses, prop thrust and torque fitted to dyno data
  • Battery sag and heat, ESC limits, rotor inflow and ground effect, wind-tunnel drag

See everything

  • Live OSD and graphs for every variable — RPM, current, gyro, temperatures
  • Record and replay flights in 3D, export to CSV, import Betaflight and iNAV logs with the DLCs

Real firmware in 3 steps (optional DLC)

Swap the built-in controller for real Betaflight or iNAV running on your PC — same physics, real code.

Betaflight
  1. Build the SITL from Betaflight source: make SITL_X_PLANE
  2. Run betaflight_SITL_X_PLANE.elf
  3. In SITL Forge: External FC → Betaflight → Activate. Betaflight Configurator connects to ws://127.0.0.1:6761

iNAV
  1. Install iNAV Configurator — the SITL is already inside
  2. In SITL Forge: External FC → iNAV → Activate
  3. Run inav_SITL --sim=rf --simip=127.0.0.1 --chanmap M01-01,M02-02,M03-03,M04-04 — the one-time CLI setup is in the in-app guide

System Requirements

Windows
SteamOS + Linux
    Minimum:
    • Requires a 64-bit processor and operating system
    • OS: Windows 10 64-bit
    • Processor: Intel Core i5-6400 / AMD Ryzen 3 1200 (4 cores)
    • Memory: 4 GB RAM
    • Graphics: NVIDIA GTX 960 / AMD RX 560 (Vulkan 1.1 support required)
    • Storage: 500 MB available space
    • Additional Notes: RC joystick is recommended
    Recommended:
    • Requires a 64-bit processor and operating system
    • OS: Windows 10/11 64-bit
    • Processor: Intel Core i5-10400 / AMD Ryzen 5 3600 (6 cores)
    • Memory: 8 GB RAM
    • Graphics: NVIDIA GTX 1660 / AMD RX 5600 XT
    • Additional Notes: RC joystick is recommended
    Minimum:
    • OS: Ubuntu 20.04+
    • Processor: Intel Core i5-6400 / AMD Ryzen 3 1200 (4 cores)
    • Memory: 4 GB RAM
    • Graphics: NVIDIA GTX 960 / AMD RX 560 (Vulkan 1.1 support required)
    • Storage: 500 MB available space
    • Additional Notes: RC joystick is recommended
    Recommended:
    • OS: Ubuntu 22.04+
    • Processor: Intel Core i5-10400 / AMD Ryzen 5 3600 (6 cores)
    • Memory: 8 GB RAM
    • Graphics: NVIDIA GTX 1660 / AMD RX 5600 XT
    • Additional Notes: RC joystick is recommended
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