What is the "Enter Mod Codes" thing on the pause screen about? Do you plan on releasing these mod codes? Love the game! Like others have said, though, the controls are VERY slippery. You find yourself compensating for movement in one direction just to slow down and change direction. Hard arcade arena shooters should be simple to control, as the skill is in avoiding things quickly, and using your mouse with this tactic to aim and shoot at the same time as doing all that.
I found a bug, by the way. Once you earn 25 gems, you can buy the next gun, AND the one after that, as 25 gems aren't deducted from your accrued total, rendering the first upgrade pointless, as you can imme3diately afford the next one, too. Once you have over 100 gems, forget about it. xD
Was I the only one to find that when I was moving, sometimes it felt like it was queuing up your key presses and mouse clicks? Like..
Let's say I just held left and kept shooting to the right, and then started pressing UP, then RIGHT, and kept firing.
It would take the game time to do all that, meaning that wherever you're clicking at the time is lagged behind all the other actions you performed. If you wait a while, it's like watching the game being played for you. xD
The life-bar doesn't fill up completely, sometimes zombies disappear due to a sprite limitation, if you click fast enough, you can make the first bullets you fired disappear. O_o Going off the screen far enough makes you invincible, although it's pointless because you can't see/shoot anything and collect the gems.
That's all I've found so far, and I've enjoyed the game immensely, even WITH the bugs I've mentioned. 3.5 stars, but only because this game has the POTENTIAL to become a 5 star game. The bugs and controls are what's bringing it down 1.5. Awesome work!