You don't need to catch them all, just certain ones, but those ones you REALLY need to catch. Or someone else will catch the ones they need and then the game will be over. Plus, think of those poor pokemon, stuck in a maze, all alone. Just dreadful.
Explore the house. Trigger the betrayal. Survive! Or betray! It sounds like a simple formula, but this cooperative to potentially competitive board game in its third edition will give hours more of chills and fun.