Fun, but clunky interface. 2/5 because no matter how good gameplay is, if you can't play smoothly it sucks (example: if I have my hero selected, i have to select a tower (which requires 2 clicks instead of one) and then deselect the tower.)
3/5 only because of the bugs. Fix those, make the turret automatic (aka hold down the mosue button to continue firing, I never use it or upgrade it because I'm too lazy) and the ability to buy repairs at LEAST for the main building, perferably for units and the towers too, and it's an easy 5/5.
Fun game. Music goes nice with the area, but gets a bit old after a bit. Would be nice if the potions stacked instead of taking up so much inventory space.
First off, don't call it racing, since it isn't really racing. I'd suggest variety: powerups, the road changing, different (tougher but less frequent) enemies, etc. Mix it up a bit, right now it's a bit...plain.
Detection is bad (sometimes I'd put a gem on one card and it'll go on another,) the instructions are lacking, and the wording sounds like it came out of a crappy translator.
 "Sola Rola - The Gravity Maze"){kind=icon}
 "A Walk in the Park"){kind=icon}
 "Toytown Tower Defense"){kind=icon}
 "Flash Empires"){kind=icon}
 "Super Bob-omb"){kind=icon}
 "WetBasement"){kind=icon}
 "Hero RPG"){kind=icon}
 "Platform Bounce"){kind=icon}
 "Jigsaw 2.1"){kind=icon}
 "Bubble Boys"){kind=icon}
 "Super Smash Flash"){kind=icon}
 "Speed Run"){kind=icon}
 "Magic Five"){kind=icon}
 "Ak47 Target Practice"){kind=icon}
 "D-Evo"){kind=icon}
 "/- TBA -/"){kind=icon}
 "Breach"){kind=icon}
 "Headless Havoc"){kind=icon}