Back in the day I playtested this game concept under an NDA, but since it expired I can talk about it.
An FPS game in an open map with buildings, has 12 players playing but when someone dies, they respawn right there but swap to the opposite team. The last person to get shot gets eliminated and then the teams split again. This goes on until 6 players are remaining, who are declared the winning team.
You could mitigate that by coms only being proximity and no indication of how many players each team has. Thst would also make offensive playstyles preferable.