This feels much more satisfying and well-tuned than the original Sanctum - and the addition of co-op takes it to a whole new difficulty level.

Saints Row IV [Steam store page]
While Saints Row: The Third was fun madness, this sequel adds a superhero twist with great new abilities and much easier travel than the previous game.

Dead Space 2 [Steam store page]
Much better and scarier than Dead Space, good atmosphere. The camera isn't sluggish and not as close. Combat also seems more responsive, and melee is somewhat possible. The 'Force' is useful, though sometimes the item you're holding disappears.

This feels like a console game - smoothed movement, unchangable (close up) third person perspective. The combat is also poor and frustrating - with guns that seem like they were meant to be used with auto-aim. Melee combat is completely useless.

Defense Grid: The Awakening [Steam store page]
A carefully balanced tower defense game with excellent voice acting that weaves an interesting story throughout the campaign.

It looks nice and is enjoyable, but could use some tweaks especially at the more advanced levels. A bunch of enemies in a row can tag team your resources quickly down the line from quite a distance away - which feels a bit cheap at times, especially since the resources travel much faster when rubber-banding to an enemy unit.

It also would be nice to have more control over tower targeting priority, or even just a manual targeting mode. For example, in the later levels you want guns to tear the shields off targets before the lasers attack them - but the guns stay focused on a target until it is completely dead even if they aren't doing effective damage.

It's still one of the better TD games out there though, excellent polish and balance.

Anomaly: Warzone Earth [Steam store page]
A tower defense role-reversal where you control the attacking units. It lacks the ability to stop or reverse your units, leaving you to determine the route and do repairs and special abilities. A bit unforgiving, requiring no casualties on normal.

Shadowgrounds [Steam store page]
A reasonably fun top-down shooter with a sci-fi storyline. The NPCs occasionally block your movement during combat - luckily they don't seem to take team damage. The flashlight also runs out of batteries slowly, which pulls you out of the game a bit.

Revenge of the Titans [Steam store page]
A tower defence game that keeps you on your toes. There are tons of upgrades and not enough time to buy all of them - you definitely won't get through all the levels on the first try.

Extremely inaccurate guns - worse than Counter Strike: Source - which makes it nearly impossible to kill anything at range without several clips of ammo. At close range it takes 2-3 head-shots from 4ft away, which is ridiculously bad. Decent story though.