The HaZardModding Coop Mod allows you to play the Single-Player Story and all the Secret levels Co-Operatively in Multi-Player. Supporting up to 8 players via LAN or Internet. Each Player can chose one of 3 Classes with specific abilities, to support the Team. Using the Tricorder primary scan mode when close to a Player, will activate the specific Class ability.
The Readme that is included in the latest Coop Mod release. Except that this version of the Readme is updated as soon as there are more Details added.