This game feels very much like Pong, but made much more engaging through a greater variety in gameplay. Each stage is fairly long, consisting of a barrage of pixels set to that stage's unique background music and concluding with a stage-specific boss fight. The flying pixels that you must guard against use a number of new behaviors, such as nonlinear flight paths, grouping, and time delays. At four stages, the game is a bit short-handed on content; for this reason, I would recommend waiting until it's on sale.

As far as tower defense goes, I have to say that this is probably the best I've played. Levels are well designed, sometimes difficult, and require much more thought than the traditional strategy of slapping down an S-shaped maze and calling it a day. Many new enemies and new towers give the game variety, and are introduced over the course of the lengthy campaign, even into the last missions. While the game is singleplayer-only, leaderboards, additional challenge modes, and special restrictions available for nearly every level lend themselves to the game's replayability. If you like tower defense, there's no question that you should buy this game.

This was my GOTY when it came out in 2010. Tight controls, hundreds of excellently designed levels spread across seven worlds, a killer soundtrack, and overall high-but-fair-difficulty are the big features of this game. Levels are short, so while you will be dying a lot, you'll make it further and further through the level with each attempt, and you'll always want to try "just one more time". If you're competitive, there are leaderboards for individual level completion times. If you're constructive, there's a level editor that lets you publish your custom levels globally to an in-game browser. For a two-man project, the quality here is absolutely stunning. Really, this is about as good as platformers get.