Activate the following cheats by entering the corresponding codes:

CHEAT FUNCTION - CHEAT CODE
99 of each weapon - pumpyouup
Nine lives - meowmeowlikemeowman
Nine continues - eatmorebran
Display framerate - framerate
Original version - letsdothetimewarp
Level select - idbuythatforadollar
Access first five levels - fiveeasypieces
Stick figure mode - hatman
Joke screen with programmer picture - iddqd or idkfa