Cost of upgrades is too high and the gold per kills ratio makes no sense.
0 kills =>1175 gold, wave done with a lot of kills => 1650 gold?? Getting killed fast and often seems to make money faster than when playing waves through. This is with maxed gold upgrade btw.
Ver buggy: Waves bugged sometimes and Quality changes to low randomly. Turrets sometimes shoot far beyond range and sometimes dont shoot anything.
prices/power is unbalanced
Yup, sounds like someone divided by zero again, we'll get this fixed soon.