I really can't tell why i keep playing this game, i think is the amount of thing you can create maybe. Remembers me when i was younger and played LEGO and roleplayed as some random characters. That's cool i guess.
Here's a tip for new players in the game:
If you want a new hero and gonna spend your credits on the game, first, test the free ones, if you have sure that you gonna buy the paid hero, oke.
 "Mutilate-a-Doll 2"){kind=icon}
 "FoE:Remains"){kind=icon}
 "Kingdom Rush Frontiers"){kind=icon}