Thief Deadly Shadows? Ugh that game stunk.
My five would be :
1. Kingdoms of Amalur: Reckoning. Like Skyrim with an action games combat. Got panned, but I put forty hours into it, and will play it again sometime. End game was pretty easy if you min/maxed your character.
2. Prototype. Started on consoles, but on the PC, and one of the best sandbox games I've ever played. The movement around the city with running up walls, gliding, or simply stealing a military copter was fantastic. Got panned for graphics, but looks awesome in a huge battle scene with tanks, helicopters, and multiple varieties of infected fighting it out. Could be very hard also; which I loved.
3. The Saboteur. Another port, like GTA WW2 with a focus on explosives and destroying Nazi everything (thousands of things). Cool graphic effect of going to grey-scale when in Nazi controlled areas except for red. Great game, and even has an official nude patch (you start in a burlesque house).
4. Defender's Quest. An indie tower defense game, but instead of towers, you place characters like archers, mages, and fighters. Done in a pixel style, so not much graphically, but a pretty damn good tower defense game, even though it requires some grinding late game.
5. Spectromancer. A fantasy card-strategy game with a lot of depth. Pretty simple graphics, but challenging and interesting. Could use more cards though.