Very good game, like the controls. I like the little bit of variety in the space map where gravity is different. I also have a few suggestions, like a hard mode where you can't rely on the flag to get your shots in, and wind. I would also suggest more variety in the maps, like more versions of the space map on different planets, and maybe which map you're on changes the way the ball moves by affecting spin and bounce. Also suggest adding more balls which bounce and spin differently for variety.
What's the purpose of the timer? I don't get it. This is already basic at best. A time clock make it worse.
Very simple and nice game