Ruined by DLC.
-An unusual combination of tower defense and 1st person shooting.
-Towers can be arranged in interesting patterns depending on the map.
-Switching to the overhead view and using it to make plans and teleport is fun.
-The perfect type of game for co-op play.
-Befitting graphics and music without any real flaws or surprises. I also found the sound effects to be slightly above average.
Bad:
-Coffee Stain Studios is charging people for the downloadable content of this game. Normally I wouldn't have any qualms about it, but such a large portion of the game is DLC (all but 2 maps) that Sanctum feels like more of a demo than a complete game. The developers should be ashamed for resorting to such a vicious marketing ploy and I hope players will think twice before buying it.
-Certain enemies can only be killed if you snipe them in the head first, this forces you to use your sniper rifle every match. It will also frustrate a lot of new players since it's not very obvious unless you read the enemy description.
-Aside from choosing your towers and guns at the start of the game, there just isn't much customization capability.