A great combination of music, nice visuals, and a unique style of light strategy. Easy enough for casual players, with Bastion type difficulty settings.

For me this game fell somewhere between Legend of Grimrock and Legend of Grimrock 2 - not quite as good as the open-world of the second game, but Vaporum's voice acting made it more of an engaging experience than the original Grimrock.

PAYDAY The Heist [Steam store page]
A fun co-op experience. The latest AI patch made it much easier to play without all four players being human. Enemy AI still has nearly perfect aim, but the body armor balances nicely if you use cover. You earn new guns and upgrades as you play.

The tone of this game is somber. The primary goal in most game modes is to cause the greatest loss of life in your opponents as possible. There should be more freedom in unit selection, and a more detailed scoring system that rewards strategy.

Left 4 Dead 2 [Steam store page]
Even though Killing Floor doesn't have a story line I still prefer it for co-op fun. This is incredibly easy, and the scripted way the special zombies pop out next to you is annoying unless you have the maps memorized.

Frozen Synapse [Steam store page]
A challenging turn-based squad tactics game, though sometimes the previews are completely wrong. Sadly, game invites pop up even when you're marked unavailable or playing single-player. You must completely exit a level to adjust resolution or sound.

An interesting blend of FPS and tower defense. Seems geared toward multiplayer, and probably fun in that aspect. Novel controls - easy once they're familiar. Flaw with anti-aircraft guns - they all shoot at the same target, needs better AI for that.

Team Fortress 2 [Steam store page]
I wanted to love this game, but found it hard to get into because it requires team effort (mainly a healer at your back) or you die exceptionally fast. Unlike Unreal Tournament or Counter-Strike: Source where you can easily play a quick lone wolf match

Atom Zombie Smasher [Steam store page]
Fairly easy on default, yet nearly impossible to win without using the chooser or combatant modifier - since it often gives you a poor selection of mercenaries. The balance could use a bit of work, since chooser lets you faceroll - but overall fun.

Plants vs. Zombies GOTY Edition [Steam store page]
A fairly relaxing arcade game - while repetitive it can get tough on the endless levels, especially right before each of the endless achievements. Would be nice if the game remembered your choice of plants between levels

Counter-Strike: Source [Steam store page]
More realistic and slower paced than some other shooters. The guns also tend to be less accurate than your normal video game for realism, and shooting while you run is nearly impossible. Still, a reasonably fun multi-player FPS.

Age of Empires II HD [Steam store page]
One of my favorite RTS - though it does suffer from the rock/paper/scissors syndrome once you know the game well enough. Age of Empires II: Conquerors Edition was a great expansion to the original game, and it's bundled into this HD remaster.

The main benefits are that this runs nicely on high resolution - the original was locked at something like 1024x768, and this also has a few tweaks like allowing higher unit maximums - raised from 200 in the original to 500 in this remaster.

I'm normally not a huge fan of re-releasing old games, but this one was such a classic, and the small tweaks they made improve the experience without ruining the nostalgia.