Haha oh no, poor Superku!

The radar needs improvement (IMO), the range is too small and I think you can replace it with a better overall concept. I can imagine that it's hard to take the objects' heights (/ z-component) into account, too, but you could try to have f.i. a 3dimensional radar.

Then, I would like to see it when no enemy is targeted but there is one on screen, that the game automatically selects him.

A black hole would be a nice graphical effect. It could have an impact on gameplay, too. Rockets, asteroids, dust und ships could be sucked into the darkness, getting bigger and thus stronger in time.