Tom Clancy's Ghost Recon !
This tactical shooter is missing in my collection. Same for Rainbow Six as well.

Mine is quite a big list. These are the games I am most looking forward to a chance to own.
None of them jump out at me like Time Commando, Strike Suit Zero, Unreal 2, NWN2 or STALKER did, to be day one (or even full price) purchases, but they all look like they would be fun games to play none the less.
With most I would be happy with a 60% discount, but others a lot more.

Jazzpunk (75%+)
Risk of Rain
Zombie Shooter 2
Zombie Shooter
DROD 1 + 2 + 3
DLC: The Japanese Incentive
Spellforce 2: Demons Of The Past
Papers, Please
Super Hexagon
Aqua Kitty: Milk Mine Defender
Theme Park
Speedball 2 HD
Broken Sword 5 - the Serpent's Curse Season Pass
Deponia 3: Goodbye Deponia
Dustforce
Dragon Lore: The Legend Begins
Battle Worlds: Kronos
Rogue Trooper
PixelJunk Shooter
Swapper
Dracula 4: Shadow of the Dragon
Carmageddon 2: Carpocalypse Now
Long Live the Queen (75%+)
Descent 3 + Expansion
Descent + Descent 2
Memoria
The Raven - Legacy of a Master Thief
Amnesia: A Machine For Pigs
Shelter
Hammerwatch
Shadowgrounds Survivor
Magrunner: Dark Pulse
Chaos Overlords
Hocus Pocus
Deadly Premonition

On sale on Steam finally, first of Ghost Recon or Rainbow Six series down to -75% must be mine :-)
But I think if one of both goes to -75%, the second will be at the same time.

Sanitarium: Only game left on my wishlist that I definitely feel I have to get.

Wishlisted some 20+ other games and will keep buying random stuff on discounts 70% off and stepper, but aside from Sanitarium I'd say I'm happily decked out and since I'm only rarely if ever interested in new releases, things are probably going to stay this way.

Jazzpunk
SiN Gold
The Banner Saga
Blackguards Special Edition
Spellforce 2: Demons Of The Past
Teslagrad
Snapshot
Long Live the Queen

Basically titles that I won't splash out on at full retail. Though Spellforce 2 might get an exception if I get into those games before a sale and become hooked.

Games that can't run on win7 or above like Heavy Metal FAKK 2.

Don't need Ghost Recon anymore ! Now on GOG I'm waiting sales for Rainbow Six and SWAT 3 !
And next sales for Full Spectrum Warrior as well :-)

Give or take one or two. XD

Populous2: Trials of the Olympian Gods
Populous
7th Legion
Downfall
Warlords Battlecry 2
Children of the Nile Complete
Independence War Deluxe
Independence War 2: Edge of Chaos
Depths of Peril
Risk of Rain
SiN Gold
Lands of Lore 3
Lands of Lore 1+2
DROD 1 + 2 + 3
The Ballads of Reemus: When The Bed Bites
BloodNet
Teslagrad
Lone Survivor: The Director\'s Cut
Shadowrun Returns
Theme Park
Freedom Force vs. the 3rd Reich
Tomb Raider: The Angel of Darkness
Ethan: Meteor Hunter
Cultures: Northland + 8th Wonder of the World
Smugglers V

unreal series -75%

Currently waiting for the following to go on sale:
7th lgion
Eschalon Book 3
Project Eden
Banner Saga
Blackguards
Heretic Kingdoms: The Inquisition
Battle Worlds: Kronos

American McGee's Alice.... Oh wait...

The complete Ubisoft catalog 75% off .

Whichever new ones are released with regional pricing.

<ba-dum-TSSSHH!>

Don't really have a list. I mean, there are some titles in my wishlist but I've passed-up sales on those before. I'm more of a random buyer.

Defcon.

It is one of the first indie games added to GOG's catalog and I saw it on promo on 2 maybe 3 occasions. Other, newer indies get discounted frequently but this one keeps its $9.99 and dosn't even blush.