Over the past few months I have been working on a multiplayer 2d shooter in XNA. I don't have a title for it yet, but the game is playable and you can download the beta and try it out. There's no instruction manual per se, but you basically load up the game, and start a new one (host) or join a game from the list. Also set your player name, it gets confusing with a bunch of Roy G. Bivs running amok.

I'll be online testing at various times this weekend. Drop me a line over IM and we can set up a game to play. My AIM is agent mu and gtalk is agent moo.

Sign up on the game forums if you'd like to post suggestions, bugs, or just get updates on the progress of the project.
Agentmoo.com forums

Requirements:
Windows XP
DirectX 9 or better Video Card
http://agentmoo.com/games/mooproto/setup.exe ( 27MB )