I would have said Diablo 2 but it's getting very old now. Then I saw that Maplassie said Titan Quest and even though I've only played it single player I can imagine that it must be fun to play co-op.
Also maybe you can try Sacred 2?
A lot of people also enjoy playing Neverwinter Nights 1 and 2 multiplayer.
It looks very dated by today's standards. I think maximum resolution is 800x600 if you have the expansion installed... that's if I'm remembering correctly.
Diablo 2 LOD remains the best game that I've ever played but it really is looking very old.
I'd go with Titan Quest or Sacred 2 so long, well up until Diablo 3 is launched!
Diablo 2 doesn't have a resolution mod pack?? All the old Black isle games have resolution mod packs so I can play them in 1680x1050 wide screen. Even though when they were released they only supported 800x600.
I didn't like diablo , prefer baldur's gate so no idea if d2 has a mod pack.
diablo2 if you want a really challenge in co-op mode ... there is a patch that is gona be released for d2 which might cater for higher res ... i dont think there is another rpg game comes close to the difficulty level in hell of d2, you need co-op to finish hell ...
titan quest is also brilliant for co-op mode but lags after an hour's play, since the people that make the game broke up there was no patch to fix it ... there was however a community patch that fixed alot of issues with TQIT, you can give that a try ... another thing, if you go the TQIT route, use the xmax mod for some hectic fun and challenges
neverwinter nights 1 is also cool, tho its kinda too slow for my liking, but once you get into it, its gona drain your life away ... i dont think neverwinter nights 2 is co-op hey :|
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