This video shows all the playable levels in the June 15th 1997 prototype version of Crash Bandicoot 2. There are 10 levels and one boss battle. One warp room is available immediately and another one with three additional levels can be unlocked by inputting a code. The remaining three levels can only be accessed with gameshark codes. Click the link at the bottom for information on how to access these levels. There's also a download link for the prototype.

Most of the levels only have minor differences in box placements and enemies. The biggest changes can be found in the three levels that require gameshark codes to access. Hangin' Out has a completely different level design and Ruination is also notable for having no boxes. These levels are also highly unstable as they can glitch or crash at any time.

First warp room:
0:00 - Startup and menu screen
0:45 - Cortex hologram
1:08 - Snow Go
3:32 - Rock It
5:05 - Bear It
6:40 - Hang Eight
8:44 - Taz Tiger

Second warp room:
10:20 - Turtle Woods
12:27 - Cold Hard Crash
15:58 - Crash Dash

Gameshark levels:
18:22 - Sewer Or Later
21:03 - Hangin' Out
25:20 - Ruination

Information and download link: https://hiddenpalace.org/Crash_Bandic...)