ColorTD is not just another tower defense game.
In ColorTD you have infinitely many towers because they are made from colors. Each color adds something to tower like red is responsible for damage while green makes tower shoot faster. Moreover if you will combine severall colors tower will have special abilitys like crit or poison.
Ontop of that there 4 upgrades that modify or completly change meaning of the colors.
Try your tactical thinking on 20 levels. Experement with infinatly many combinations of towers. Just download it try for youself.