you should make more maps with new props, maybe make a map thats a house and if its outside you could make the time of day, add flashlights, pistols, more taunts, easier chat, aiming down the sights, and other stuff that will take about 10 years to make.
This is one of my favorite TD game, probably because its the only one i've pretty much played for more than 5 min... but still its a great game and like Kame554 said, the graphics don't matter, I actually like them so GREAT GAME!
 "Everybody Edits"){kind=icon}
 "Reincarnation: Riley's Out Again"){kind=icon}
 "Hunters and Props"){kind=icon}
 "Demons vs Fairyland"){kind=icon}
 "INXSYS"){kind=icon}
 "CS Online (^beta version^)"){kind=icon}