slow overall gameplay
very well done, but the game plays out *very* slowly until the final two levels, where it suddenly jumps pace and the player is suddenly rushed with 100+ foes. Very nice work on the final boss. Game played smoothly and the game mechanics were sound. I'd recommend you have some bosses that look a bit different, however. (you have multiple species-looking smaller space-craft, but the bosses all follow the same general style). Planet development was a bit lacking, however. It was a unique concept, but I would have appreciated more steps to the terraforming process that progress at a faster pace. Also, some more plannet upgrades (IE: spike on chain, volcano-cannon, etc) would a welcome refresher from the current two. Some notification about what powerup you just got would also be usefull, I'm sure 95% or more of the people who got a nuke pressed the button to activate it when there were no foes on screen just to see what it did.
all in all: quite sound game mechanics, beautiful visuals and effects, and a charming presentation. Plenty of room for improvement, but that's true of every game.