PROJAM (latest version 4.4) is a mod for AvP2 that redefines all the skins, sounds, physics, and gameplay for both the Multiplayer and Single Player experience. (Multiplayer requires that the server and all users are running the mod)
To install: create a folder in your Fox\Aliens vs. Predator 2 folder called "custom" (without the quotation marks).
Put PROJAM4_4.REZ in this custom folder.
Run avp2.exe. At the opening menu, click Options. In the command line, type: -rez custom/PROJAM4_4.REZ and make sure you've selected "Always these command-line parameters." Now when you run the game, you should be playing PROJAM 4.4.