Hey I played this earlier but forgot to rate and comment...understandably incomplete since this is for SMVM, but I'll highlight what I thought was really enjoyable - I think shooting is done well here. I like how it feels, I like the gravity and ping-pong effect on the projectile. It's the root mechanic of what could be a really fun game. I did feel that the player moved a little too fast for ease of control - that's only me, so check with others. Maybe the platforms are too small for the player to move comfortably.
My only advice as time goes on till SMVM is to make sure you keep things in scope, and don't skimp on a narrative to keep the player engaged. You don't need 10 more mechanics - a nice shooting mechanic is actually good enough. Instead, focus on a couple of other simple abilities, then work on other elements of gameplay.
All the best for SMVM!