This game sure does have a steep learning curve. I'd recommend you add a symbol to the colored areas, which represents what they do. For example a fist for strength (red), a bull's eye for range (blue), a stopwatch for recharge time (yellow) and a thermometer for cooldown (green), and possibly the stat the color decreases in red or with a minus symbol next to it. It's rather hard to remember each effect, at least at first.

The other thing I'd recommend is that you remap the controls. The location of z and y is different in parts of the world (qwertz vs qwerty keyboard), and it's a bit difficult to play with z where y is on your keyboard.

Now don't get me wrong. The game is actually good and enjoyable, It's however difficult to get into at first, and first impressions count. If you improve the way you deliver the instructions, it'll make it accessible to a much wider audience. (I actually didn't know it was a tower defense game when I started the first wave, 'TD' is not as obvious as you'd expect)

Very clever interpretation of the theme and quite fun, but I'll agree with errorage, very difficult to figure out what to do. Some more "easing into things" would've been nice.

Nice game, but really hard! I enjoyed the difficulty though, the graphics are crisp.

One thing, the Close Button doesn't close the game. Overall great job!

It seems overpacked with features. I don't like the tower recharging, I think you should make one game with drawing and another with recharging. Also, colors are difficult to remember. At least let us use the 'shift' hint when we want, and don't throw us to level selection when we do so.

I really like the idea and the level looks really interesting after drawing some stuff in it.

Also agree that a little more needs to be added to the color to indicate their function. However nice way to incorporate the minimalist artwork!

Could have done with some music but enjoyed a few rounds of this :)

A bit difficult to figure out at first and lots of crazy keys to press (may have been nice to leave the legend for the keys on screen or easily accessible) but once I figured it all out though it was quite a fun game and a clever interpretation of the theme.

I'm on a Mac, sorry :(

Nice game, well done!