Great game. It feels really rewarding to watch the replays after you've completed a level. I think this is the only game in which I've ever bothered to watch a replay
Loved the game but I have 2 complaints/suggestions;
The one thing I had most trouble with was the shield unit. I found it hard to control properly and whenever I had to use them it was more frustrating then fun.
I think this unit would benefit from a mouseaction, for example: if you hold down the mousebutton the shield would lock in it's place (release button to have it act normaly). This would make it abit easier to control and make it more fun imo.
R restarts the unit. But if you die at second 9 of your last guy and your not fast enough to press R, its all over. Frustrating to have to redo all your previous runs when it all came down to that last one. It'd be great if R would restart your last run even if time was out.
Other then that, just some music, make it remember your resolution settings and add shitloads of levels. This is the type of game where 100+ levels could work. With the leveleditor (havent checked it out yet) maybe you could accept submissions from players to include in the finalgame.