Perfect dose of 5 minute vs ungodly rage for me. Soundtrack is awesome: a simple, repeating theme, growing in complexity and harmony every time. Also death from the red eyes is horrible. I love it.
The winning strategy that works for me every time is to terraform eerything into a plane to build as much castles as possible, and then switch to attac mode to blow away the enemies. No thinking necessary.
Are you aware that there is already a quite popular game named shift? I'm not saying you did it on purpose, but it's disturbing and misleading, for me at least. I just wanted to make you aware of this.
ArmorGames' Shift: https://www.kongregate.com/games/ArmorGames/shift
You can really feel the sense of achievements every time you give them the DED. ;)