Fierce

In Fierce, you play as Zena and Piper - two women fighting in the zombie-robot apocalypse. Switch between Zena and Piper at the press of a button - switching between their different fighting styles to slay your enemies in different ways. At the end of each wave - choose who to upgrade, but be carefull - each character has limited stamina, meaning you must utilize them both in order to survive! Don't put all of your eggs in the same basket ;D