Better than expected

I can't tell you how happy I am to see Just Cause 2 in this list. And in first place, too! :D

JC2

Just Cause 2.

The Binding of Isaac:)

Hahah, he asked for more suggestion, not for a game from the list. :D

Give Psychonauts and Brutal legend a try.

Most games played from an external HD will have lag due to the lower throughput of the USB path.
Play a game that has low disk access and lower character models to load.
Welcome to the dark side of gaming now that you have a Windows environment. LOL

Alice: Madness Returns

Both Torchlights

No idea if you've completed Tomb Raider 2013 yet, but according by your gameplay time, I'll assume not. You should, though. Great game. :)

Mount & Blade / M&B Warband

Sleeping Dogs

Dragon Age

Fallout NV

Rogue Legacy

Vampire:The Masquerade (You should install the community patches though)

The Darkness, if you're into gory games

• Antichamber
• Bastion
• Bleed
• Braid
• Half Minute Hero: Super Mega Neo Climax Ultimate Boy
• Papo & Yo
• Thomas Was Alone
• Strong Bad's Cool Game for Attractive People.

Well, maybe you could try these games, depending on what you like :

• Point & click :
  The Whispered World
  The Walking Dead: Season Two
• Stealth game (but you can shoot everybody if you prefer) :
  Dishonored
  Deus Ex: Human Revolution
• Hack & Slash :
  The Incredible Adventures of Van Helsing
• Shooter with a (weird ?) story :
  Spec Ops: The Line
• Fun solo and Co-op :
  Orcs Must Die!
• Nice surprise :
  Papo & Yo
• Old but nice RPG :
  Vampire: The Masquerade - Bloodlines

Just Cause is a great game if you forvige their awful voices, the horrible story and cheese dialoge...

Try Tomb Raider 2013 or tomb raider annyversary, is great too

if ur into visual novels you should probably play the ones, they don't take long.

Sonic Generations definitely

Rayman Origins is really fun too

Spintires is great with a group of friends, but it can get boring pretty fast if you're not into that sort of stuff.

Tomb Raider: 2013. It could've been better, but it's pretty good for what it is. Worth finishing, in my opinion.

Saints Row 2, How to survive, Orcs must die! 2, Trine Complete

The Witcher 1 and 2,
The Elder Scrolls IV: Oblivion ,
The Elder Scrolls V: Skyrim,
Max Payne 2

Filtering to games we both own and you haven't played a minute I could recommend this:
Alphabetical order:
BioShock
Fable - The Lost Chapters
Hero of the Kingdom (I liked it for some reason)
Legacy of Kain: Defiance
Portal
The Elder Scrolls IV: Oblivion
And did you not play Half-Life 2? (1.6 hrs on record) or you played it before? :)

Ok from the rest of the games you own and I don't and you haven't played at all:
Dishonored
Dragon Age: Origins - Ultimate Edition
Fallout: New Vegas
Hitman: Blood Money
Home Sheep Home 2
Neighbours from Hell 1&2 :D
Spec Ops: The Line

• Deus Ex Human Revolution + The Missing Link (The Missing Link starts after certain bomb goes booomb in the main game)

• Tomb Raider (2013)

• The Elder Scrolls V: Skyrim

• The Walking Dead: Season Two

• Prince of Persia (2008)

Europa Universalis III-I haven't played IV yet but I spent over 200 hours with this one.If you check my games you will see I don't own it on steam, but bought the Complete box when it came out a few years ago.

Mount and Blade:Warband -Perhaps the greatest sandbox game ever made. Almost as moddable as Neverwinter Nights (the 2002 game) and with a sequel on the horizon that promises to deliver even more, get stuck in.

Crusader Kings II-Had GamersGate version vanilla and built up a 300 year old dynasty, then when it went steam-only I quit to focus on other games, have logged over 25 hrs on it in the last couple of weeks due to picking up the DLC pack thanks to a recent sale, well worth the time investment.( In fact I should really get back to my game.)

Play GTA IV

Play the Max Payne games :P.

Also, batch 2.

Batch number two!

Go with the batch which has Mafia