This is really good, very addictive.
It could use some music though.
Also I was a little dissapointed to find out there were only three levels in the "level mode". Perhaps after you become a big enough star you could become a black hole, then a super massive black hole, then a galaxy, then a bigger galaxy, and so on...?
Regardless, I'm having a good time with this game, the survival mode seems to be rather devoid of rocks and planets small than yours, I've only manager to get up to 29.13 so far, but I'll keep on trying :)
One more thing, and I'm not sure how much you have to do with this, but on the "Hall of Fame" there is a place for your name, the date, and a place for "time" which seems to determine your score. However it doesn't seem that time has anything to do with it, it would seem that all that matters is how big you get, yet it does say "time" on the "Hall of Fame". I'm just wondering if that was an oversight or if there really is a reason for it?
Anyway, great game, I'll probably be playing it all day :P