Defense Grid 2 adds some wonderful new mechanics to what is arguably one of the best tower defense titles ever made.
The Nerd Stash: "Everyone loves setting up killzones and laying waste to waves of enemies, so here are our picks for the best tower defense games ever."
It's also free to try on the mobile headset and Oculus Rift.
Tower defence games have become incredibly popular on iOS and Android devices over the last few years but they are also incredibly fun to play on your PC.