A long time I read about some "next generation" 2-stroke thing, where they had fuel injected directly into the cylinders, after the piston had already blocked the exhaust port. The intake port was only used for air. A bit like those behemoth 2-stroke marine diesel engines.

Evidently it didn't really work out well enough, considering most outboards they sell these days are 4-stroke. I've always had a soft spot for 2-stroke engines, seems so wasteful to "waste" half of the strokes on a 4-stroke. Oh well.