A great game, in my opinion. The design and concept are lovely, and I always enjoy smaller game companies. I used to adore tower defense games in my earlier years, but after I discovered Steam, I started to drift away from the tower defense games I'd play online. I started to play more FPS-Type games such as Gmod, Half-Life 2, and TF2. One day I closed a steam game, and was greeted with the exciting sight of a steam news window. Scrolling through it, I came across a "newly released" page featuring Sanctum 2. All I remember was that the picture had Skye on it, and I thought "Oh, this is interesting character design. I'll check this out." (Yes, I'm a sucker for gingers.) So I watched the trailer, then eagerly waited for the demo to download. I bought the full game shortly after clearing the demo, and I was not disappointed.
A note for those with less-than-behemoth GPU's, since the creators don't have a huge amount of resources availible, they don't have all that much spare time for graphical optimization, so it may get a bit choppy with the higher settings.
TL;DR: Cute gingers, strong female characters, perfect genre (For me, at least.) And shiny art style. 11/10 would buy again.