One of the distinguishing features is that they don't need valves to operate. That's to say, the Wankel rotary engine design doesn't have valves -- but quite a few rotary engine designs have ...

This means it is a reciprocating rotary engine. Yeah, weird stuff. The camshaft is also centrally located in the crankcase and still runs at 50-percent crankshaft speed but only actuates one valve ...