Villainous is essentially a reverse tower defense game. Instead of setting up towers to defend against creeps, you send out the creeps to infiltrate your enemy's defenses. In each stage, there is a limit to how many units you can summon. Your units, like towers in tower defense games, have strengths and weaknesses. Knowing the strengths and weaknesses of your units will help you determine the order in which to send them. In addition to summoning units, you can cast spells when you have enough mana. Mana is generated over time and can be collected in the form of orbs that are released by fallen units. After each siege, you will gain infamy, which is a currency that allows you to unlock and upgrade units and spells.