I'll throw in my two cents
It would seem logical that there would be some sort of coal to collect and a furnace to deposit.
Also logical would be a physical element that represented water, and one that represented steam.
Turning gears and pipes should be included and a airship/blimp/dirigible would not be too much of a surprise.
So here is a concept that also incorporates Archimedes 3 shapes that the FIRST Logo is based on.
Game pieces
"Red hot" coal =red cones
Steam particles = white spheres like whiffle balls
Water particles = blue cylinders.
Teams would have to collect and then figure out how to sort the objects...which would be rather difficult since they all have at some level a circle with the same radius.
Coal/red cones go in your alliance furnace,
Steam/white spheres go in your alliance boiler
Cold water/blue cylinder goes in the other alliance's boiler to "cool them down"
End game is a dirigible that has to turn a gear or reach a goal.
There are dirigibles for sale on Amazon that can pair with a cell phone. It doesn't seem to unrealistic to think that you could pair them with your robot.
Dirigibles are way way easier to fly and control than drones.
The motors, battery and pairing connector would come in the KOP to level the playing field. Teams would choose the inflated lifting device.
Dirigibles would be stationed on the field and only come into play at the endgame.
Coach of Team 3023