Reach will be fun. But not very unique as you wanted. I've been playing Just Cause 2 now for a month. It's not even fun anymore, but I can't stop playing. So for a highly addictive game, try JC2.
Otherwise Reach and DR2 will be the best to come.
Now that I think about it, I played some EDF with a friend of mine Saturday. That game is a blast. Very simple and highly addicting. Lots of fun.
I am considering Black Ops since I saw the wager match trailer. That looks fun and I like to gamble HAHA. THough I am not as competative as a lot of guys with FPS games so I might get owned.
I you guys haven't played it before. Playing together is essential. You can have multiple characters going at once, and theres an ass load of missions to do.
Note: If your characters are seperated by more than 3 lvls the lower level will have a tough time surviving and the higher level wont gain xp!
Wish i didn't delete my game now! FUUUUUUUUU level 42/50 siren...
Reach looks like it could include literally hundreds of gametypes through ForgeWorld if people get creative. I'm sure there are plenty of people here who are inventive enough to think of a few.
Here is a video of the Korean version of a game called AVA. If your computer can handle it (it utilizing Unreal 3), I suggest you get it for the PC, from IJJI.com.
Its like a mix of CS and a LITTLE bit of Battlefield.
You can choose 3 set classes and switch in game, Pointman (SMGs,carbines, and shotguns), Rifleman (assault rifles and battle rifles) and Sniper (bolt-action, semiautomatics, the VSS).
The Demolition game mode is basically old fashioned plant the bomb.
Annihilation is team deathmatch with fixed spawn areas.
Its a little slow on the west server (my server) now but if you live out east you get a ton of rooms.
Don't be put off by supposed comparisons to MW2, the main community also hates that game. Besides, guns in this game have upwards off-center recoil.
The only real problem is that you have to invest a lot of ingame currency in the permanent weapons (that you must repair for a slight cost). This gets tricky when you want to get many weapons. If you want to have them all you will need to pay real cash, or spend a few months ranking up to LT while spending money wisely.
Borderlands is AWESOME. I mean my brother and I have played every DLC they have released and maxed our characters and still can't wait for the next DLC to come out.