Best games on Steam Sale right now?

Hey guys,
I'm looking for a new game to play and since the Steam Summer Sale is going on right now I figure I might as well stock up. I'm currently looking for an RTS but would be open to other genre's if they're really, really good. My budget is probably <$20 per game and I'm open to buy more than one game if they are worth it. I would also like something I can put some serious time in to and that hopefully still has a fair amount of people playing online (I prefer online over single-player).

Games I've been thinking about so far:

- Civilization 4 or 5
- Rome: Total War
- Supreme Commander 2
- Magicka
- Left 4 Dead 1 or 2
- Far Cry 1 or 2
- Knights of the Old Republic

I know Magicka's an RPG/adventure game but I heard it's really good (can't remember where I read it but I've heard good things). Same with KotOR. I know L4D and Far Cry are FPS' but I've also heard good things.

So...what do you guys think? Thank you!

Far Cry 1 is good i would get that,FC2 was a bit...poor in comparison imo.

Also if your wanting Left 4 Dead,I would just get the second one...its basically the same as the first but better i think.
Not tried any of the rest so i cant comment.

I have L4D2 and Magicka. I can recommend L4D2, especially if you know someone who also has it. You can play just fine with strangers and have a lot of fun, but it can be a bit frustrating at times if one or more people run ahead on their own or start trolling.
Magicka is pretty good, the sheer diversity of spells that you can cast is impressive. The spells can be very powerful and because of this you have to be careful, unless of course you don't mind accidentally killing yourself.

I've played Far Cry 2 and I can not recommend it. There are some interesting ideas there, but the execution isn't on par.

Haven't played KOTOR, but I've heard very good things about it. Due to it's age I would suggest having a look around the KOTOR section of Steam forums and the official KOTOR forums for any info on how well it runs on newer versions of Windows.

KOTOR is a great and fun game. Haven't tried on Windows 7 yet though.
L4D2 is awesome.
Great RTS would be AoE3. Civ IV isn't Realtime, but Turn Based. Still good fun though. I've heard IV is better than V from many but I'd advise looking at the differences for yourself. I've only played IV.

Fallout new vegas and fallout 3, oblivion goty. These will pretty much consume your life.

LFD2 has several of the maps from LFD so basically you are getting half of the first game when you get the second.

KOTOR 1 and 2 are awesome. 2 has you going to many of the same places as 1, but it's a great set of RPGs. Especially if you are in to star wars.

LFD2 comes with all lfd1 maps doesnt it?

skyrim, fallout 3 new vegas and batman arkham city is what I bought. I love them. Skyrim and fall out 3 all came in a bundle for $50.00 and arkham city was only $10 dollars.