The
Strife "teaser" demo has some notable differences from the starting part of the full game, although it's not an entirely new level set. The demo is also based on an earlier version of the engine,
as indicated by the people behind the reverse-engineered source port of the full game. On the whole, the demo of
Strife gives a glimpse of what seems to be an early version of the starting levels in the game.
Download Strife teaser v1.0 and v1.1