It's fairly straightforward, you pick a side Predator/Prey then you add or subtract from the current score until one side has won (with a score of 20 (prey) or -20 (predators). So for example...
Starting point 0
@Ravofox posts -1 (normally predator) -1
@DRGN Juno posts -1 (predator) -2
@Thrashy posts +1 (normally prey) -1
@TR273 posts +1 (prey) 0
@Groggy posts +1 (prey) 1
..and so on.
This is broken up with periods of shitposting in-between rounds until someone starts a new round. Rounds consist of roleplay, history lessons, bad jokes, worse art (mine usually) and generally attempts to undermine the dignity of the other side.