Here you can see the last minute changes between the 0.99 beta that was leaked on the internet a long time ago and how it compared to the first public 1.0 shareware.

While it might look like a lot is the same, every level hides many changes inside them.
Most of these include extra features and detail that got cut from the game to squeeze out the best possible frames per second.

Level 1

Hollywood holocaust

Level 2

Red light district

Level 3

Death row

Level 4

Toxic dump

Level 5

The abyss

Secret 1

Launch facility