Sanctum is the world's first FPS tower defense game and is set in a beautiful science fiction world. You take the role of Skye, an elite soldier sent out to protect her hometown, Elysion One, from hordes of mysterious alien creatures. To facilitate your success you construct defensive structures and upgrade handheld weapons. Jump right into the fray and wreak havoc with your own weapons - unlike regular tower defense games, you are a key part of the defense. Sanctum has taken the best features of first person shooters and tower defense games to create something totally unique.
This one's big fun! Not much of a story (didn't find any at all, so far), but especially the multiplayer rocks.
The TD/FPS blend feels like it was made especially for (people like) me: in other TD games, I always got bored when I could only watch my setup of towers go against the waves of enemies without being able to be involved in the actual fight. So, along comes Sanctum's FPS part. Even the controls work unexpectedly well, considering TD is almost on the other end of the scale to FPS, especially control-wise.
The difficulty is well balanced and hard and insane mode offer enough challenges to keep players occupied for a long time. The new levels, weapons and towers that came with the latest update added a lot of play time, since you can now try different tactics with the same optimized mazes.
Sadly, they haven't introduced any new enemies via updates so far and the old ones do grow old after having played every level twice.
But there's still a lot of fun to be had with this game, first and foremost along friends, building the perfect maze and, if neccessary, preventing that one big tank to get to the core last second with combined assault rifle fire power.