You just did a mediocre copy of the excellent "Vector TD" from David Scott.
The Game is great. I'm literally playing just to get on the leaderboards for each level. You should make some more tracks too. The music is pretty good but I think at least 5 tracks would be good to vary for players. I could listen to this one song all day though so good job on that.
Finally, a good strategic TD game that focuses more on tactics than having cute characters or premium content.
Difficult right from the start! You really need to think about where you put those towers. Idea's simple, level layouts varied, and the onslaught... pretty challenging compared to most of these games! Good fun though... for a while... with the easier difficulties. ;)
The graphics aren't the greatest, and based on your early demos, I liked the early look a bit better. But I love this game overall, and man, it gets hard at about round 40.
Haha, thanks man! What are your thoughts on the music though? ;D