I had an idea for a jail escape where the guards lose if all the prisoners die. They're supposed to stop prisoners from escaping in non-lethal ways, like setting up traps or roadblocks, and they only win if time runs out and there are living prisoners still locked up. I mean, in a real jail, you'd be in some serious trouble if you murdered every single prisoner.
Maybe if you had a really huge map, and guards could close off particular sections to slow prisoners down. You could block off one hall and then prisoners would have to dig through a wall (slowly) to get around it, or find another path to take. Actual physical encounters between guards and prisoners would be rare, and guards would only kill prisoners as an absolute last resort. This would eliminate any freekilling business, since all you'd be doing by killing random prisoners is making your team lose.
You'd have to disable ctrl-k for prisoners to keep them from insta-winning by killing themselves, and be really strict about AFKs so guards don't just kill all prisoners except for an afk person and wait for time to run out.
I haven't been able to put an idea like this into action to see if it actually works but I think it's a step away from the traditional jail game.