Of course, it would probably require different billiard balls, like a whole bunch of one color and a whole bunch of a second. Or I suppose one person could take odd-numbered balls and the other could have even-numbered balls. Probably would be a good idea to take note of the different balls ahead of time in case one falls in and you didn't catch which one it was.
Another idea for a game could be "field pool." Same cues, but large rubber numbered balls, and it's played on a football or soccer field. Or instead of cues, one could use cricket bats or feet. Make up your own details from there. :-)