Thanks for the kind comments (and yes, I hate it when a game need a reset to play again... I'm fixing that soon, when adding some menu screens).
The rebound is really silly, as the yoyo could not possibly justify it, but it's from the original game. It adds something in the way of platforming, as killing enemy requires you to mind ledges, so I'm keeping it. I think the original spent some thoughts about the thing, like with the mechanic where running plus shooting is risky: the yoyo stays too little and too near ahead of you and colliding with enemies becames more likely. But then again, it's the natural consequence of the back and forth coded in the simplest way possible, so maybe they just went with it.
I'plannig to expand on yoyo mechanics, like giving higher scores or guaranteed drops for kills with a trick shot (like hitting when the yoyo is coming back to you), or using some vertical momentum.