Stuck on the third floor because I don't have a key... Do I have go through every room of every floor to make sure I have enough stuff to continue? Sucks that I can't go back down a level, but I don't seem to be able to do anything else here. Walked through all of it 3 times now...
I'm a big fan of TDs but this also makes me picky...
I think the game is a little too linear, flamethrower and especially sharpshooter(sh) seem to be OP. Shs are always worth to build about 50 of, cause they are cheap, dont take up a lot of space and are one of the 2 reliable anti-air towers.
Most levels have one challenge and from then on its easy. Also I found all the tier 2 towers a little dissapointing;huge amounts of space; very little benefit. Fill that space with shs and you are always better off.Some more balancing between costs of towers, sizes of towers, abilities and gold received would be great. Also yes it is nice to get "Stars" for each level, but by themselves they are pretty useless as a motivation.
Nevertheless I played it through and enjoyed it. As I am writing this survival mode is laaging itself through level 32 which makes me suggest some harder mobs instead of having 100k of the small ones.
 "Specter Knight"){kind=icon}
 "Swarm Defender"){kind=icon}
There should be enough keys on every floor to complete the floor. Did you check the minimap for items that you did not collect?