Crystal Defenders is a Field Runners type game with Final Fantasy characters, enemies, and environments. There are three worlds (as they call it) each with four different stages, but only 2 unique ones, the others are the advanced version of the original level. The advanced versions just include more paths for the enemies to travel and diverge on or more things are blocking your attacks, but on the upside the enemies do spawn with a little less health. You start with twenty crystals and if the enemies get to the end of the path they take one. Every ten waves they send four bosses each with the ability to take 2 crystals instead of 1.