System Protocol One is a very themed tower defense. Not only that but it does a good job creating both the tower defense and the central theme without sacraficing one for the other. The gameplay is what you would expect from a block based tower defense. You have your standard array of rock-paper-scissor enemies and towers and for the most part there is no one correct way to win. Mind you, the game can be a tad unforgiving on higher levels almost requiring you to do the "correct" build to win. And as always, there will be those who choose to juggle. I find juggling to be a cheap exploit, and if the game relys on you doing it to win then the game is fundamentally flawed in terms of balance. But overall System Protocl One is worth the price. It may be a bit too unforgiving for some, but it is still enjoyable.