The idea is simply to bring just a few simple environment variables into the game.
If a player's ball send a ball flying into the treetops there's an X% chance that it will panic nearby birds perched in the tree causing them to fly off.
If the players ball lands in the water there's an X% chance that an inquisitve fish will swim up to where the ball entered the water (and jump the surface perhaps).
I also think it would be cool to leave a skeleton at the bottom of the bunker for players who land in the coffins during Halloween, but that's another story...