Space Invasion Tower Defense 2

Some suggestions:
(1) Tower placement: make it snap to a grid.
(2) Mute and unmute command should be the same key. Ditto for pause and unpause.
(3) Make high scores available. (I can't find any.)
(4) Make it possible to speed up the game.
(5) Add more background pictures and spaceship types for different levels.

Strategy tips: Build a bunch of money towers, with some exploding and shock towers to slow enemies down. With the money towers, having a large number is more important than upgrading. I got to wave 87 on the Challenge level with 16 million gold. Couldn't get farther, since there was no space left to place any more towers.

Along with what others have said, it is a decent TD. The UI is pretty bad though - overlapping graphics, a very undetailed Skills System GUI. It just looks very rough art-wise. The gameplay doesn't make up for the art. There are simply too many TDs out there for this to warrant a high rating. You as a creator appear to be in the mindset of 'keep making mediocre games - as long as they have towers and enemies it'll be okay'. It isn't going to impress me or many other people. This, like many others lacks depth or a reason to play when there are other games like Gemcraft available. 2/5

reached level 9 , played again and again and lost count how many times ... just impossible to pass level 9 :(

It's a decent TD, but there are SOOO many TDs that decent doesn't cut it. The genre has been done to death, unless you've got something EXTREMELY good, or a very new idea to add to it, don't bother.....
Also, setting it in space was a mistake....reasons for creeps to stick to paths are tenuous at the best of times, in space....madness. Just another another another tower defense game...