I'll give this game 3,5 stars. Reasons:
1. Vague map. It's hard to tell what routes are possible for enemies tot take, and since you can only build one tower at time, and building takes some time, it's hard to make a strategy and you can end in building useless towers
2. There is definitely a time gap between target hit and it's health drop, wich makes towers waste unnecessary time shooting at enemies that should have 0 health by that moment
3. No database on towers, enemies, no plot after initial intro
Could've been much better