The game is 8-ball, league rules (call pocket, a ball has to drop or hit a rail after you hit the object ball, you have to hit your ball first, fouls result in ball-in-hand -- that's most of them), but the tricky part is: you're playing rotation.
Someone breaks. If they make a ball, they have their choice of stripes or solids. If they DON'T make anything, the next player has to choose.
If you're solids, you HAVE to shoot the 1-ball first. If you make it, you shoot again, at the 2. If you don't, your turn's done. If you're stripes, you shoot the 15 first, then the 14, etc. Solids work UP to the 8: stripes work DOWN.
Combinations are allowed, as long as you hit your lowest ball first. If you hit one of yours first, but not your lowest-numbered ball, your turn's done. It's not a foul. If you hit THEIR ball first, it IS a foul.
I've tried this game with friends, and it's difficult, especially if you don't have the hang of your position play. But it WILL make you learn.