All the version notes since the alpha version can be found at:
http://forums.amplitude-studios.com/showthread.php?446-Release-Notes

1.0.8
CHANGES AND ADDITIONS
- The duration of random events is now displayed in the game event panel.
- Removed the "% of colonized systems" constraint from the expansion victory requirements.
- Each effect of "Retreat" and "Offensive retreat" battle actions now lasts +1 round.
- Improved AI reaction with Difficulty.
- The Endless Hero (Corporate/Adventurer)is now more balanced fleet/system-wise.
- Memory optimization.
- Added a new portrait for the Sheredyn (Emperor Edition).

FIXES
IMPORTANT FIXES
- Fixed an issue where the cancel button in the Faction Editor saved the changes, allowing custom faction exploits.
- Fixed an issue where the Endless Hero never appeared in the Academy (Emperor Edition). The Endless Hero cannot be hired by an AI.
- Fixed an issue where two simultaneous attacks on a third player in the same system crashed the turn ending.
- Fixed an issue where simultaneous game joining crashed the turn ending.

OTHER FIXES
- Fixed an issue where the upkeep for Inorganic Cultivation (Sower) & Intensive Cultivation Logistics (Craver) was positive instead of negative.
- Fixed an issue where the number of players in a session did not take into account locked slots.
- Fixed an issue where all battle cards were played even if the battle ended before the final phase.
- Fixed an issue where battle cards were not effective in a specific case.
- Fixed an issue where a player could only request a value of dust, from another empire, equal or less than his current dust.
- Fixed an issue where hovering over a reduced anomaly displayed the reduce anomaly effect tooltip.
- Fixed an issue where a player could rejoin his own defeated session after receiving the defeat screen.
- Fixed several text issues.
- Fixed several localized text issues.

All the version notes since the alpha version can be found at:
http://forums.amplitude-studios.com/showthread.php?446-Release-Notes

1.0.5
CHANGES AND ADDITIONS
- Memory optimization. Refer to the following post for further details:
http://forums.amplitude-studios.com/showthread.php?5500-Optimizations-status&p=62704&viewfull=1#post62704
- Added collisions to graphic FX to stop them from going through ships.
- Improved graphic FX for the 'Gravity Well' Battle Action.
- Hero bonuses to attack and defense will now be correctly acknowledged through displayed MP on his Fleet.
- Diplomatic balancing (harder mainly for Serious & Endless modes).

FIXES
- Fixed an issue where negative effects on the AI’s diplomatic attitude were inversed, counter-balancing other parts of that AI.
- Fixed an issue where the Tolerance trait was displaying a wrong value in the system view.
- Fixed an issue where “Random faction” was displayed instead of the faction’s actual name on an invasion notification.
- Fixed an issue where the galaxy would sometimes not be visible when starting a new game.
- Fixed an issue where the user was unable to zoom out at maximum height after playing a few game sessions.
- Fixed an issue where the Horatio Affinity unlocked the Arid Epigenetics technology.
- Fixed an issue where the host remained stuck on the end turn action if a client joined in progress and left the session at the same turn.
- Fixed an issue where the title remained stuck on end turn actions after a manual combat.
- Fixed an issue where the users were not synchronized after a system was invaded and conquered during a multiplayer session.
- Fixed an issue where the round-ups on the tonnage modules were different than the ones on the total tonnage in the ship design view.
- Fixed several text issues.
- Fixed several localized text issues.

Endless Space Out Now!

All the version notes since the alpha version can be found at:
http://forums.amplitude-studios.com/showthread.php?446-Release-Notes

1.0.3
CHANGES AND ADDITIONS
- Changed the save file system. The previous files are not compatible.
- Added the custom faction screen.
- Added a free camera mode in the battle view.
+ Arrow keys: move the view
+ Mouse wheel: changes the camera field of view (angle)
+ Mouse right click + pan: rotates the camera view
+ Ctrl: sticks / unsticks the camera on your fleet
- You can continue to play after a victory condition is achieved.
- Added a state to the player, to know if he's in a battle or not.
- Added an animatic for each faction, which will be displayed for a new game.
- Added narrative & random events illustrations.
- Changed the illustration for the selection of "Random Faction".
- Changed the Pirates 3D fleet icon.
- Added several outgame scenes, which will be displayed randomly.
- All technologies have a dedicated icon.
- Added 5 new music.
- Added new GUI sounds.
- Added an ES soundtrack directory (in the Steam install directory of Endless Space on your computer).
- Added the ES credits.
- Texture, video, memory & AI optimization.
- Added one new difficulty mode - Endless.
- Food consumption by population will vary with game speed.
- Heroes will not be injured when retreating. Changed the 'Death before dishonor' faction trait.
- Ship levels increase HP, DamageMin, DamageMax, InterceptionAccuracy, DeflectionPerTurn and Absorption.
- Changed the ship leveling, which now requires more XP (6 to 45 -> 4 to 100)
- Decreased the defense mods' cost (3 to 75 -> 2 to 58).
- Decreased the defense mods' weight (7 to 20 -> 5 to 16).
- Antimissile and Shield mods are now more powerful than their Weapon counterpart.
- Deflectors bonuses were only slightly increased.
- Halved Defense MP (8 to 210 -> 4 to 125) but not their efficiency in general.
- Defense MP is less effective during invasions than weapons.
- Added an extra bonus on the armor mods (25 to 304 -> 25 to 220+12%).
- Modified the Bluecap mold monopoly bonus (Dust -> Approval).
- Reduced the difficulty of diplomatic victory ( 1000 + 10*(players)*(planets) -> 2000 + 15*(players)*(planets) ).
- Decreases the malus of the random event "SUPERNOVA DISRUPTS NAVIGATION MAPS" (-80% -> -30%)
- When playing sower, the player knows the actual FIDS of a planet before colonizing it.
- Decreased the Alliance bonus multiplier (Alliance : * 2 -> Alliance : * 1,6).

FIXES
IMPORTANT FIXES
- Fixed an issue where the leech hero ability will not stop upon conquering the star system.
- Fixed an issue where an assert is received when a system is conquered by the AI and the user is in System view on the same system.
- [MP] Fixed an issue where assert is received when joining an in-progress session.
- [MP] Fixed an issue where opening the war notification as host will cause an assert.
- Fixed an issue where pressing ESC after quitting a game will cause an assert.
- Fixed an issue where the game crashes 100% after loading a specific save game.
- Fixed an issue where loading a saved game from another Steam account causes an assert.

OTHER FIXES
- Fixed several text issues.
- Fixed several localized text issues.
- Fixed an issue where the browsing arrows become unresponsive in planet view in a 2 planet system.
- Fixed an issue where the moon orbiting a planet will not adjust size properly in planet view.
- Fixed an issue where the heal button is not functional on the Assign to system screen.
- Fixed an issue where a graphical corruption can be seen when entering the star system.
- Fixed an issue where the Permanent Perennials star system improvement is not working.
- Fixed an issue where the resolution will not change to 1600x900 when in windowed mode.
- Fixed an issue where the user will have the buyout option active for a ship that cannot be completed normally (strategic prerequisite or obsolete ship design).
- Fixed an issue where the amount of military power is displayed using decimals on the battle report.
- [MP] Fixed an issue where ships are displayed as being in hangar on other player`s system.
- Fixed an issue where the name of the empire is not replaced in the current deals with button.
- Fixed an issue where cease fire are not spread to allies.
- Fixed an issue where the initial starting population decreases right after the first turn at slow game speed.
- Fixed an issue where disband/create fleet does not refresh movement points.
- Fixed an issue where the race names are seen in the language of the other player.
- Fixed an issue where the Hissho Affinity tool tip is not updated.
- Fixed an issue where the United Empire Affinity tool tip is not updated.
- Fixed an issue where the "Industry to Science" conversion tool tip is not updated.
- Fixed an issue where the user is able to select guard action on an enemy`s fleet.
- Fixed an issue where technologies do not affect the deal approval.
- Fixed an issue where actual faction names were not updated in the Diplomatic Negotiations Screen when choosing random factions.

Playable Alpha Release Notes
You can find more information on our forum about the current alpha version of the game:
http://forums.amplitude-studios.com/showthread.php?446-Playable-Alpha-Release-Notes