Bowling mode sounds fun! and won't be much hassle for the dev team.
With the monsters as the bowling pins, there'll be lots of gores and blood splats when the ball strikes em. Gibs flying everywhere when you got a strike... sounds real fun! Bowling with violence! And the arena would still be the ancient civilizations themed. Sounds awesome. I'm supporting the idea absolutely.
Survival mode is kinda hard to play with current control mechanics. But bowling?
Pool/snooker in my thought it won't work, since the ball would interfere with the sights/aim.