I've started to love playing different shooter games in splitscreen mode with my friends, and especially CO-OPERATIVE with a story (the campaign). Here are something I've tried or might be trying:
Army of Two
- much fun with a friend
- the campaign is too short
Rainbow Six Las Vegas 2
- a bit difficult (too realistic?

)
Gears of War
- just didn't work very well for us... didn't like the sounds and the graphics (especially blood) and the feel of it
Dark Point Zero
- "ok" but a bit frustrating
Kane and Lynch
- I've purchased it but not played it
Halo 3
- Planning to get it, I understand it has co-op story?
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These I'm interested in:
Ghost recon 2: advanced war fighter
- does it have co-op campaign mode?
Call of duty 4
- I think it has no co-op campaign mode?
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So, anything else? You know any other good shooter games with splitsreen and campaign mode?