Nice graphics, nice layering.
The cheat option has disapeared <img src="smileys/smiley3.gif" border="0" align="middle" /> this is even harder.
Good job though. This looks a lot like a professional game. All hails C2.
Thanks. I've been following C2 since v37 and when this game caught my eye I thought it was the perfect time to jump in.
To Do List (when I get more time...):
Audio compatibility across browsers. I followed the HTML5 audio compatibility controversy but am still unsure how C2 resolved it (if it has been resolved). I used WAV files and only got OGG files out and didn't have time to look into it further.
Different backgrounds for different levels (getting darker/nightfull as the levels get faster, perhaps). I used one image for the background so would probably want to look into file size, etc. The lighting would need to change on the structures and the ground too. A little programming would be necessary too (should be simple though).