We'd like to actually do something as a community for once, in the absence of a functioning Cyberpunk roleplay. A full co-op playthrough of Half-Life, Half-Life 2, or one of the many custom cooperative Source maps seems like they'd be a fun event that most of us could participate in.

VOTE ON A GAME HERE[poll.pollcode.com]

Sven Coop
Requires Half-Life (not Source)
The oldest cooperative mod for a Half-Life game. It adds new content (weapons, enemies..) to the original Half-Life story, optimized for cooperative play in a group, along with a good amount of custom maps with the same level of teamwork.
Synergy
Requires Half-Life 2
A popular mod which modifies the original Half-Life 2 (and its Episodes) campaign to excellently support a cooperative experience. It makes minimal changes to the actual levels and gameplay, making playthroughs closer to the singleplayer vanilla. Includes a handful of custom maps.
Obsidian Conflict
Requires Half-Life 2, or Half-Life: Source (if we choose to do its campaign instead)
A mod based around general coop in the Source engine, notably including the Half-Life, Half-Life 2, and Episodic campaigns. The campaigns may be somewhat buggy, if memory serves. It also is backed by an impressive selection of cooperative and team v team custom maps; including everything from using teamwork to operate a battleship, to maintaining and upgrading a farm.

Edit
♥♥♥♥, I realized the moment after posting that I should've included links to the websites.
Sven Coop[www.svencoop.com]
Synergy[synergymod.net]
Obsidian Conflict[obsidianconflict.net]