Revenge of the Titans has now been released on Steam. i'm presuming anyone that bought the humble bundle will get a steam key for the game. not sure yet how this happens a si can't find my order details at the moment. The email is buried amongst a few thousand emails. At least I know the approximate date of purchase, which should narrow the search down. :)
It looks like tower Defence games are making a comeback, with two more TD games released over the last few weeks. Anomaly: Warzone Earth, which is a reverse tower defence game and tasks you with saving a near-future Earth from an alien onslaught. The invaders have captured world’s major cities, building huge turrets that destroy everything in their path. It’s up to you to lead an armor squad through the streets of cities like Baghdad and Tokyo, planning the route and strategically choosing which units to deploy in order to crush the opposition. Take control of the Commander, whose special abilities and quick thinking will be vital in supporting the squad in its mission, as you engage in fast-paced, tactical battle across story campaign and two heart-pounding Squad Assault Modes. Reference accessed HERE April 2011
Then theres Sanctum which is a first person shooter tower defense where you take on the role of Skye, an elite soldier sent out to protect her home town, Elysion One, from hordes of mysterious alien creatures.
To succeed you have to construct and upgrade defensive structures. What makes Sanctum unique from other TD games is that when the havoc starts, you jump right into the action with your own weapons and play a key role in the defense. Sanctum has taken the best features from first person shooters and tower defense games to create something totally unique.
Reference accesses HERE April 2011. Sanctum is still on preorder via Steam, but you are able to play the Beta that was very satisfying. :)