SO much fun. I close my eyes and see packets moving along relays.

The campaign levels are varied and sometimes very challenging, and there are thousands of user-made levels, some that introduce totally different ways to play and think about the game.

In many levels, the hardest part is the early game, when you're trying to establish your energy production as efficiently as possible. Don't be afraid to Deactivate structures that are under construction if you become power stalled!