Okay, I am waiting with baited breath for Firefall, but until it comes out I need something fun that isn't insane to get into.

I much prefer something like a survival type situation (Firefall and Monday Night Combat are fine, just I don't know if I'm up for yet another capture the flag/deathmatch type game just now).

I know Killing Floor exists, and existed pre-Steam as a mod, but the retail copy everyone plays uses Steamworks I think. This would be the kind of thing I'm looking for, though since it's class based and team based co-op. You work together to mow down gobs of enemies and avoid being overrun.

I'm looking for PC, I'm tired of analog stick shooting for now (somehow I was amazing at Golden Eye but just feel like I suck now).

I'd like something with low cheating and a cool community.

But let's not make this just about me, what do you guys think are the most fun co-op shooters and why (even if they don't meet my criteria, I'd still love to hear about them)?

Sven Co-op, perhaps?

I'm enjoying Borderlands, but i have to admit I'm playing it with just the one friend over the internet and leveling together, never bothering to ever play with anyone else (I've read the community is pretty bad). The story and the missions are just lame excuses to go kill stuff, since they all involve finding things then going back to collect money, XP or weapons. It has a cool artistic style, it has some vehicular combat, it has leveling up, skills to dock points into that augment damage, melee damage, shields, health, reload speed, etc.. and lots of weapons, meaning: Lots of reskinned, renamed, recolored models of weapons with different stats.

It's been entertaing but it's getting repetitive already and we're barely halfways. Recommend it if you have a friend to play it with and just want to shoot stuff. If you're looking for the community experience, not sure if it's going to be your cup of tea. I'm also playing it on Steam and don't know if it uses anything else. It's also a port of a console game, but it's a pretty good port regarding controls. Very simple to pick up and remap keys or use a controller.

Check some videos to find out if you like what you see. It's pretty much a Diablo rpg kind of game mixed with a shooter, sans a worthwhile story, set in another planet that looks post apocalyptic. It's always going on sale on Steam, so I don't think it's worth fetching it at regular price.

Oh, and I always really enjoyed The Hidden Source and Zombie Panic Source. But both need Steam, and The Hidden is kinda the exact opposite of what you're asking for (1 person is completely invisible and the rest need to hunt him down). As you might know, I love AvP, and it has a rudimentary co-op mode against unlimited aliens. Not the best, but can be entertaining.

I think both Killing Floor and Left 4 Dead are really good picks as well but...Steam.
Another idea: Serious Sam.

i have had great fun with left4dead, but the community is the absolute worst i have ever seen, if you play coop you are fine, but avoid VS at all costs if you want nice people

Hidden & dangerous was absolutely amazing when you could find 2-4 people to play it with. Sneaking around, doing missions, while chatting with your friends over team speak (which was what all the cool kids used back in the days ;) ). The game was quite challenging (scratch that, it was brutal), but the feeling of accomplishment after finishing one of the later missions was great.

A more recent one that I've enjoyed (ever since steam decided to give me a free copy in the current holiday sale) is PAYDAY: The heist. Think left 4 dead, but you play as criminals instead, and it is not focused on hordes of enemies coming your way, but rather a handful of enemies at a time. There are also more things to look out for in this game, things like cameras and snipers can ruin your day if you are not careful.

I was kind of afraid this was going to be the case, everything post UT 2004 seems to use Steamworks:(

Borderlands doesn't. and it's really fun too.

This. Though I think some of the expansions have limited installs.

I enjoy Tribes Ascend (or its predecessor Tribes 2). Lots of roles to assume and fun co-op to be had over teamspeak. I'll probably try to get into clan play once T:A introduces support for that.

T2 is free and without DRM that I know of. T:A will be free-to-play on launch and will to my knowledge install a launcher, an optional update service and a punkbuster-like anti-cheat service. PM me if you're interested in T:A beta keys. I think I have 4 at the moment.

I'm slightly confused. Team based co-op implies that there's more than one team, but that doesn't seem to be what you're describing. Do you just mean co-op, but with lots of players?

Have you ever played Invasion in UT2004? That's pretty fun. Finding other players for it might be difficult today though.

Well opposing teams is fun, but I was looking for something a bit different, Killing Floor is the best example I can come up with.

I accidentally bought Borderlands GOTY 2 years ago (or so) off Amazon not realizing it had activation, perhaps I should just install that and try it.

Tribes Ascend is an interesting thought, I might just try the beta for that.

Yes killing floor is a really good Co-op shooter, makes you trust in your teammate and really involves working together a lot.

Sanctum is also good. Although it's a tower defense game you still have guns to shoot the waves of mobs but it's steam only.

Rainbow Six Vegas 2 Co-op is also fun and i don't believe it uses steamworks?

Well, it's just that the Invasion game type in UT2004 is exactly as you described. Co-op against ever increasing hordes of enemies.