Despite the epic Steam sale going on, I have yet to make any purchases.  At all. 
 
I am opening this up to the GB community, hoping for some recommendations to help me cut through the mass of games on sale. 
 
Guidelines/Info 

1.  I play on Mac, so it has be Mac supported. 
2.  Its a MacBookPro, 2.2Ghz, Intel Core 2 Duo type.  Has a GeForce 8600M GT.  I take pretty good care of it, but it isn't brand new.  Runs Half-Life 2 just fine, but struggles quite heavily with TF2...
3. Check my current library on GB's achievements page
4. I will also be posting both specific questions as well as accepting general recommendations.
5. Don't just link me to GB, Gamespot, MetaCritic, etc reviews, I can read those myself, thanks.
6. I don't want to just hear "This game roxxorz my soxxorz!"
7. If you have Steam, and are incredibly useful in your recommendations, I will gift you a game, limit of $15 USD.

Despite the epic Steam sale going on, I have yet to make any purchases.  At all. 
 
I am opening this up to the GB community, hoping for some recommendations to help me cut through the mass of games on sale. 
 
Guidelines/Info 

1.  I play on Mac, so it has be Mac supported. 
2.  Its a MacBookPro, 2.2Ghz, Intel Core 2 Duo type.  Has a GeForce 8600M GT.  I take pretty good care of it, but it isn't brand new.  Runs Half-Life 2 just fine, but struggles quite heavily with TF2...
3. Check my current library on GB's achievements page
4. I will also be posting both specific questions as well as accepting general recommendations.
5. Don't just link me to GB, Gamespot, MetaCritic, etc reviews, I can read those myself, thanks.
6. I don't want to just hear "This game roxxorz my soxxorz!"
7. If you have Steam, and are incredibly useful in your recommendations, I will gift you a game, limit of $15 USD.

Torchlight is a good game to play. It's Diablo clone done by the original creators of Diablo. This game is also able to run on a netbook. So your Mac can run it just fine. There's also mod support for this game too. People create all kinds of characters and levels. But I'm not sure if there is mod support for the Mac version though. Look it up. Another good game is World of Goo. Its pretty unique with its puzzles. Basically you have a bunch of goo balls that you have to stack up and get sucked into a tube. Of course theirs obstacles. It's an indie game so it'll run on your Mac.

Counter Strike Source is a ton of fun, its a great team based fist person multiplayer shooter, the combat feels really good and it has a huge community (Even larger than that of TF2 at 70 thousand players logging on every day). The main game takes alot of effort to warm up to but once you have you'll love it, also, it has a fantastic mod community, so if you dislike the main game there are always other sources of fun. (Maybe that is different on Mac, i can't be sure) 

Ya i Would say Torchlight is a great choice.  However it is only good if u are the type of guy who likes collecting things and loves looting 
Red Orchestra is a Very Realistic WW2 first person shooter it  doesnt  have the best graphics and while i havent played it i can assume that it is pretty well optimized and u can run it 
Bioshock is 5$ i dont know if u have played it but its one of the best games of the last decade.  it may be a struggle for ur rig but its totally worth playing even on low settings 
Dragon Age Origins is another game where its iffy if u could run it or not but is a blast to play if ur willing to try it and like games similar to Baldurs gate 
Thief deadly shadows u most likely could run and is a fun first person stealth game that is 3$  
Unreal Tournament  2004 is a really fun old school Competitive FPS with lots of mods for it its a great deal for 8$ 
Personally i love counter strike and am sure that u could run it pretty smoothly if ur into those types of games
BUY HALF LIFE 1 its one of the greatest games of all time and u could easily run it very smoothly.  i replayed it last year and it held up very well 
Day of Defeat is pretty cool 
Left 4 Dead is completely fantastic but you probly would have some trouble running it

 
Sam and Max is an obvious choice too. Well written, compact, and with some of the best music and voice acting you'll hear in a game. Both seasons work standalone, or you could buy episode by episode. I think the fourth has been released for free to promote it, it's definitely worth checking out, if only for the "War" song. Seriously, youtube it. 
 
Mac gamers still have a raw deal, but between Altitude and Torchlight, I can keep busy when I can't get to my PC.

It seems you already own many of the good mac games, but there's some stuff that I can't tell if you own or not.
 
 
Counter-strike Source: the ultimate multiplayer FPS. Recently updated with new achievements and content. If you like shooting dudes, get this game. 
  
Sam and Max: A parody of... everything. Witty dialogue and funny puzzles. 
 
Civilization IV: I could play this game for days. It's fifteen bucks right now, and at that price, it's insane. It doesn't require knowing all of the game mechanics to have a good time with it. I still don't understand everything but have played it for countless hours. So addicting. 
 
Braid: If you buy none of the other games, buy this one. Some of the puzzles may get really hard and occasionally frustrating, but there's an amazing feeling of accomplishment after finishing it. Add to that lush visuals, absolutely brilliant music, an ambiguous yet touching story, and an awesome conclusion and you get an amazing game that goes on my list of  "Best Games of all Time."

" Despite the epic Steam sale going on, I have yet to make any purchases.  At all. 
 
I am opening this up to the GB community, hoping for some recommendations to help me cut through the mass of games on sale. 
 
Guidelines/Info 

1.  I play on Mac, so it has be Mac supported."

" @ch13696: @JellyFish_Gsus: @CowMuffins:   Great recommendations, so great I already got them!  Although I will say World of Goo hasn't impressed me as much as I thought it would, Torchilght, on the other hand, I really like. "

Get Peggle and Peggle Nights for Mac for $10.49.

Looking at your game list it seems like Half Life 2 is your favourite. I would first and foremost recommend the expansions to that game. They add more of the gameplay you know and love with more added to the story and a few twists to boot. It wraps the whole experience up nicely. 
 
Since I also enjoyed Half Life 2 quite a bit, I can recommend to you one of my favourite games, BioShock. It really has an amazing story, beautiful graphics and fun gameplay. People complain about its gameplay but man that game was remarkable. It's on sale today so I think you should buy it now. 
 
I'm not sure how much you like RPG's. I am a big fan of them and can easily recommend to you Oblivion and Fallout 3. Oblivion is my favourite game of all time. However, I told some friends to play it and a couple of them said the game was too slow for their liking and they never really got into it. It certainly has that feel of the lone hero in a huge world (the one present in Half-Life) as does Fallout 3. Both games were made by Bethesda so there are similarities but they are very different games. Your rig should easily run both of these games.  
 
If you end up liking Oblivion you can shell out a few more dollars for Morrowind, however they are both the same type of game and are both very long so you may not want to jump right into the same world again.  
 
Another game I would suggest, even though I never played it, is Dead Space. It certainly is a beautiful game and it certainly seems to give the atmosphere of being alone. I always wanted to play the game but I am quite a pansy :P People who have this game love it. I don't think I heard one negative review for it. Your rig should be able to run this game at the mid level.  
 
EDIT: Awesome, I just realized that none of these games are mac supported :) my bad

Might I recommend Altitude? 
 
It's a pretty fun multiplayer 2D aerial combat game. It can run on just about any computer as well.  
 
Bonus it's only $3.40!

" @SuicidalSnowman said:

" @ch13696: @JellyFish_Gsus: @CowMuffins:   Great recommendations, so great I already got them!  Although I will say World of Goo hasn't impressed me as much as I thought it would, Torchilght, on the other hand, I really like. "

Yeah, I dunno why everyone seemed so enamoured with World of Goo. I liked the music and general art style, but I never found it to be actually fun.  Anyway, glad to have helped. "

If you're into point & click adventures at all I would highly recommend Tales of Monkey Island. It's not on sale at the moment but It probably will be by the end of the sale. I wasn't old enough to play the first Monkey Island games but I figured I'd give Tales a shot after reading Ryan's review of the first episode. I enjoyed them so much that I went back and bought the Secret of Monkey Island remake. I've never really played too many point & click adventure games before other than Maniac Mansion on the NES and Grim Fandango quite a while ago, so it was quite a surprise that I enjoyed Tales so much. I found I could hardly wait for the next months release to continue the story. Kinda makes me wish I was old enough to play the original run of point and click adventure games. I'm eagerly awaiting the remake of Monkey Island 2 and the next season of Tales.

You seem to own all the good stuff already lol, but in any case:
 
Counter-Strike - I wouldn't call it the ultimate in the FPS genre, but it's certainly no slouch.  Let's put it like this, what shooters can you think of that came out in 2004 that still have thousands of people logging on each day? Not many. So you're guranteed to have have tons of people to play with 24/7. And despite the 'hardcore assholes' rep this game has built up, there is easily a ton of people out there willing to play with you, teach you some tricks, and well...generally not be assholes towards you lol. That's a win in my book. Plus it just got Steam achievements so another instant win right there.
 
Half-life Expansions - Not much to say here. If you loved Half-Life 2, you'll love these. Episode 1 is a blast. And Episode 2 is even better. I was a bit skeptical when people made a big deal out of how awesome the outdoor environment was, but after playing it multiple times I can safely say: it's freaking amazing. There's a lot of space, a lot of good puzzles, a lot of good battles, a lot of everything really. You won't be disappointed. Well, not unless you're expecting Episode 3 any time soon. 
 
Eve Online - Not sure how much you enjoy MMOs, but if  you're curious then I suggest giving it a shot. It's hard to describe this game in detail as the objective of the game is whatever you choose to make it. Wanna become the best pilot in the game? Learn everything there is to know about flying. Wanna become the most popular trader/craftsman around? It can happen. Wanna create of group of pirates and rob anyone who flies into your sector? You can do it. Wanna cause a war between every player on the server at the same time? Never happened, but it's in the realm of possibility. The only thing stopping you is you. People claim that it's hard to catch up to veteran players, but that's not true. Veteran players just know more skills. That doesn't mean they know how to use or can use for that matter.Some skills are completely useless when it comes to certain ships.After about a month of training skills, if you're smart about it, you are easily just as valuable to a fleet as someone whose been playing for years. The game also has one of the best communities in any game. Helpful and very mature as this game tends to weed out the weak-willed very early on...EDIT: Forgot to mention that the learning curve is quite large. It's not difficult, but it's just big. Luckily there's a tutorial for everything so you should be fine. If you are curious but not 100% sold, there is a 14-day trial on Steam and you can get a 21-day trial if you can get an invite from a current subscriber.

I recommend Killing Floor. It's a really fun co-op game that's like a more realistic Left 4 Dead.  It has quite a lot of maps to play on, an active online community, and the gameplay is great fun with realistic-feeling guns.  There's a ton of fun to be had on co-op, also, It goes up to six players, and the perks and different character models are fun to play around with and add a really nice level of customization. Really great art design as well. It's $10, and it's well worth it. A lot of content.

It's an indie game so it'll run on your Mac. "

zeno clash.

Not on sale:

On Sale:

Did any one get a game, or did you bouy a game ts?