Although I'm not a fan of Tower Defence games (it's not my style), 20 Waves by Colin Lane does change the genre slightly and offers a lot of fun in a freely playable browser based game. But what makes this game so different from the others? Well factor in that it's not top down and it's 2D based, but turrets, force fields, and walls need to be placed against the oncoming waves from the sides to defend your mining operation. It's that simple!