Here is a prototype of Skate 3 for Xbox 360 from about 4 months before final, it's a debug build (sk83_na_m works) - credit to Tuukas, Kran and Games Past for the recovery efforts, and Tdijital for dumping the HDD in 2020.
Notes:
- A debug menu is accessible with LT + Back.
- Adding kbDebugFE=1 into startup.ini gives access to test maps not found on the final release.
To run:
- Only sk83_na_m.xex works.
- Requires removing fileserver.ini.
Known issues:
- Exiting the Trick Guide causes the game to freeze.
- Some challenges crash the game. The debug menu can be used to complete them.
- Some cutscene animations play incorrectly.
- Entering Freeskate causes shadows to disappear.
Differences
- This build is significantly closer to Skate 2 than the final game
- Movement is generally closer to Skate 2, offboard movement is still early
- Lighting is different, being a mix of Skate 2's lighting and the finals. More noticeable in certain areas
- Almost all of the locations in the challenge map were renamed for the final
- Compass doesn't work yet
- Score UI has a different design
- Hall of Meat mode bails don't cap the game to 30fps like the final
- Loading hints and stats don't exist yet
- Grind-Vision setting in video settings from Skate 2 that was cut from the final game, seems to function here
Screenshots:

