A wizard duel game. 1v1. The gimmick is that you have to do the somatic (arm waving) component for your spells to fire. Could work with VR controllers or even a Kinect. The longer your arm travels, the stronger the spell becomes. You, as a wizard, can "create" a list of somatic components and attribute them to an effect, like "fire" or "darkness" or "lightning". By mixing and matching your waving, you could cast a variety of spells with different effects, like a lightning bolt that sets the enemy on fire and engulfs them in darkness. To avoid being hit, you could either finish a counterspell faster, hit the enemy with an appropriately strong spell (at least 1 somatic component less than his current casting) or set up shields that will absorb a number of damage before dissipating.

To make the game fancy, you'd be able to customize your wizard and your wizard tower, both of which would be the centerpieces of the duel. Everything you'd unlock through gameplay, no battlepass bullshit, no microtransactions, no bullshit grind to make it last longer than it should.