Batman: Arkham Asylum; Arkham City and Arkham Origins
Mafia 2(currently playing is funky)
Assassins Creed 4: Black Flag

metro last light and dead space are pretty cool

S.T.A.L.K.E.R Shadow of Chernobyl + Call of Pripyat

euro truck simulator 2 is incredibly under-rated. assuming you can make it through your friend's ridicule

Tomb Raider fo 5 dolla

http://www.gamestop.com/pc/games/tomb-raider/103028

I really like Mark of the Ninja

If you like RPGs you can get Persona 3 (FES/Portable) or Persona 4 on an emulator.

A few that haven't been mentioned yet:

Mirror's Edge
The Banner Saga
Trine
Fallout (New Vegas is good)
Spelunky
The Swapper

Both kotors are pretty amazing, as many have said.

Jade Empire is really good, and you probably haven't played it yet. It's from the makers of the first kotor.

backing up spelunky, binding of isaac, and terraria

humble bundle is really good right now as well, dust and antichamber are fun

half-life, quake 1, quake 3

If you're into Indie games I recommend:

The Binding of Issac
The Basement Collection
Rouge Legacy
LIMBO
Don't Starve
Deadlight
10,000,000
FTL: Faster than Light
Spelunky
Terraria
Super Meat Boy (you need an xbox controller)
Orcs Must Die 1/2
Super Crate Box
Home
Quantum Conundrum

Metal Gear Rising: Revengeance and Resident Evil 4. both perfect games. and if you buy these maybe more Japanese developers will get their games on Steam.

Mount and Blade Warband

I would recommend Total War: SHOGUN 2. I found it more enjoyable than Rome 2 and if you have a good computer it looks great. (Also on sale at the moment)

Baldur's Gate 1-2
Mask of the Betrayer
Planescape: Torment
KOTOR 1-2
The Swapper
Dark Souls

The new Tomb Raider is a fantastic experience, would fully recommend.

sez who? I use a gravis gamepad lol

http://upload.wikimedia.org/wikipedia/commons/e/e6/Gravis_pc_gamepad.jpg

it's almost as old as I am

thanks for the suggestions guys, really appreciate it!

dragon quest 8 on an emulator
Both Alice games
Dark Souls with dsfix
Jet Set Radio

games I have on steam:
cave story, skyrim, magicka, prince of persia 1-3, splinter cell: chaos theory, tomb raider (newest), antichamber, borderlands 1/2, mirrors edge, return to castle wolfenstein, beat hazard, 140, fez, limbo, terraria, trine 1/2, half-life & portal games, black mesa

I don't think that's singleplayer

the singleplayer is just fights vs. bots, but i find myself playing it pretty often to relax. if you're looking for actual levels, definitely pick up quake 1

aka the only DQ that's good

also suikoden - play this series

hotline miami
la noire
starbound
scribblenauts unlimited
antichamber

These are the ones i like

Football Manager

I would suggest the newest Metro Last Light. One of the best all around games i've ever played. Amazing graphics, amazing story, titties and a lot of combat scenarios. Very impressive game.

I'm very similar where in between seasons i'll look for some games to change things up a bit. I've found pleasure in the following:

Batman Arkham City
BioShock Infinite
Borderlands 1 & 2
Deus EX: Human Revolution
Dishonored
DmC Devil May Cry (Different, arcade style)
FarCry 3 (MUST HAVE!)
Lost Planet 3
Saints Row The Third
Tomb Raider
Dead Space 3
Crysis 3
Skyrim
Mass Effect 3

Right now i'm checking out Tom Clancy's Splinter Cell Blacklist, so far so good but a little too sneaky for my taste. All of the above were great games though.

I've also never played magic in my life but i'm enjoying Magic 2014. It's cheap too and chews up a lot of free time. I'd definitely go for Metro and FarCry first.

Just saw FarCry3 on sales 75% off, jump on that for sure!