I enjoy this - you should consider doing something more with it, I think :)
I absolutely agree with Stephen Lavelle, the concept is nice, but a little more would be definitely better. I'd say to get the other circles some degree of AI. And maybe powerups? Or stages?
Your feedback means a lot to me guys, thank you! I will continue working on this game and others as soon as I get rid of my bachelor's exams this summer...
This is a really neat concept man! Whilst I agree that this game could be developed more, I absolutely adore its minimalism right now. Great work. :)
This is a really clever game, and it takes a certain amount of finesse to figure out. It reminds me of fencing. Great job!