I thought it would be nice to brainstorm some ideas for either future official FIRST games or maybe off season team built and run games so then maybe someone will read this and maybe actually use these ideas or just for fun. One idea that is probably what you are thinking of generally speaking is some sort of water game. Although their are problems for water games, this is for ideas and is kinda a thought experiment that may lead to useful ideas.
My idea is basically a capture the flag type game where you drive boat type things with small arms or hooks that can steal a flag from an opponent but to do that you must match or go faster then they are or drive perpendicular to them but they could easily turn away from you so their must be a speed restriction of some kind. The more time you hold the flag in your hand, the more points you get but you get double the points while it is inside of your “base” which is basically just a marked area that anyone can drive into no matter which alliance they are part of.
Another is a race type game where you have to race people while picking up items that you can use to give you points or “power ups” like a temporary increase in your max allowed speed but be careful to not keep going to fast or you will lose points. Or you can bring an item to the end of the race to subtract a certain amount of time from your time making so your race time is faster. Another is to temporarily decrease how time runs for you. Basically your time will be measured like it passes more slowly.