What video game "engine" was used to make this?

My longest run has been of about an hour, and couldn't find the boss nor the compass to find the lair. Any tips or help please ):

is it dead or alive ? any updates soon ???

Where's he?

Why in the world can they? You aren't excalty able to place any towers after you kill him thus its nearly immposible to pick up the chesrt and the skull needed to contiune. Side Note: Arches are way too annyoing mostly because my minions just refuse to attack them and ingore them forever...