Here are my latest 5.

Spec Ops: The Line - Fun 3rd person cover shooter. Think Gears of War but with normal-sized people instead of dudes that could flip a truck by themselves. Also less chainsaws, sadly. I got it because of the reviews stating how hard-hitting the story was. I tend to disagree and feel that it is very heavy-handed and isn't very enthralling. Still, the core mechanics of the game are enjoyable enough and I'll finish it at some point. Probably not worth a 2nd playthrough, however.

Space Hulk Ascension - Adaptation of the board game Space Hulk, which takes place in the Warhammer 40K universe. You command a team of 5 to 10 Space Marines that have earned the right to wear Terminator armor - basically huge, genetically modified super soldiers that have survived potentially hundreds of battles. Weapons include flamethrowers and rocket launchers, as well as less flashy bolters and power fists. Your enemies are part of the Tyranid swarm known as Genestealers. They have big knife hands and run fast. Gameplay is turn-based and each mission has your squad(s) closing bulkheads to force the enemy into choke points, planting explosives, or holding out against droves of filthy xenos, all while in very cramped conditions where the wrong move can spell doom for everyone on the mission. I would highly recommend picking it up if you enjoy turn-based games and Warhammer 40K.

Tropico 4 - Sim City on some Caribbean islands during the Cold War between the US and USSR. You play as a dictator of an unknown Caribbean nation, starting from nothing but a few shanties and progressing into an economic powerhouse. Like Sim City, you have to build places for people to live, work, and play. However, you also need to build farms and ranches for food and exports, manage the affections of various factions on the island, and ensure that the US or USSR don't try to invade you. Gameplay so far has revolved around completing a specific goal on each island, such as getting $X of exports, building a tourist trap, or making sure that you win when election time rolls around. Once you win, you can move to the next island or continue on your current one. I had a previous island sending aid to my new one, so there does seem to be opportunities to help yourself in the future based on how well you do in the present. Very enjoyable city-builder.

Supreme Commander: Forged Alliance - Massive scale RTS. You start with just a commander unit (ACU) and build a base that will roll out endless masses of units to overwhelm your enemies. Speaking of mass, the primary resource and limiting factor in the game is the collection of mass. Extractors can be build on various predetermined locations on each map, pulling in a set amount of mass for as long as you can hold that point. Energy is much easier to acquire. Building power plants will supply you with energy necessary to power shields, radar, and personal teleporters for your ACU. Structures are upgraded in tiers, with each tier unlocking a new builder unit that can build all of that tier's structures. (e.g. a T1 engineer can build a T1 factory that can upgrade to a T2 factory to produce a T2 engineer that can then produce a T2 power plant or any T1 structure.)

There are 3 normal tiers and a 4th experimental tier, unlocked once you get a T3 engineer or upgrade your ACU's engineering suite to T3. Each tier significantly increases in power. A T1 power plant, for instance, produces 20 power/second, whereas a T2 produces 500 power/second, and a T3 produces 2500 power/second. Units work in the same way. A T3 land unit will have much more firepower than a T1, and will be able to destroy quite a few of them before it goes down. Experimental units are your faction's ultimate killing machines. There are giant robots with laser eyes and magnet hands that will destroy entire bases in seconds if left unchecked, flying saucers with an internal air factory to produce swarms of fighters, as well as AA missiles and a giant air-to-ground laser beam à la Independence Day, or huge artillery guns that can fire all the way across the map. The maps can be as small as 5km x 5km up to the massive 81km x 81km. Unit plus building cap is 500 per player with an 8 player limit. Games last anywhere from 8 minutes to 2 hours, depending on skill and how you like playing. Extremely fun game. Small player base unless you download the free mod FAF (Forged Alliance Forever) that hosts its own games and provides balance patches. I haven't had any experience with FAF, though. Only what I've read.

The Fall - 2D puzzle game where you play as the AI of a combat suit that was brought online due to the pilot that is wearing you being mysteriously incapacitated. I haven't finished this one, but so far it's very dark (literally and atmospherically) and seems to bring up the question of the lengths an AI should be able to go to protect what it's being assigned to protect. Minor spoilers (~10 minutes into the game) follow: One of the first situations involves you having to purposely take fire from a turret in order to bypass a safety restriction of your internal programming that doesn't allow you to manually activate any defense systems in the suit unless a human authorizes it or if the human pilot is placed in mortal danger. End spoilers. I find the game to be very intriguing and the puzzles are just the right amount of difficult. Very cool and interesting game so far.

Edit - Botched the markup. Going to try and beautify it a little bit more.