Something I've always wanted is a optional toggle system that would allow particle collisions to enact force onto world objects or even player collisions.
Particle Systems are already built in with a option to send messages via collision to which we currently don't really have full access to so I think implementing something like this would be fascinating to see in action.
So what exactly would this system allow us to do?
My idea would be something along the lines of a force function, allowing "world props" that are designated to do so to receive a bit of momentum from avatar particle impacts.
Let's say for an example, a sphere world object with a gravity function. If say, someone is using an "explosion" particle. it would open a new level of interactivity if that explosion particle could LAUNCH that world sphere forwards based off the speed and angle the particle collider is coming at it.
How could this affect Players? Well, if enabled via either world creators or personal preference(*),based off the player's pillbox and whether or not that player is grounded. Allowing us to effectively bounce off these colliders I think would be an excellent edition.
*I would definitely note to have a limiting function in place that would have it functionally the same as to how "player interactivity" is already designated via the quick menu. Just something to keep it from being full on annoying. I'd imagine very few people would want a random person to launch them back. HOWEVER, in that same ballpark, many definitely could say that having the equivalent of "rocket jumping" with friends would be FUN.
It'd also be safe to set a max of how many particle collision force checks are allowed at once for both optimization and preventing anyone and anything from launching to Saturn. Though I think that's something you'd have to experiment with to really say how much is a good number.
In any case, I don't really expect this to be an "any time soon" thing or even to gain traction. I've never really suggested a feature so if you took the time to even read this, thank you! Overall, have a good day.