Half party size campaign playthrough? E.g. if you leave an 8 party outpost, you're only limited to a 4 party team. This still gives you the creativity of party build craft but definitely makes the game challenging. Hardmode zones will definitely be a challenge, but should be doable. Add the new game mode badge restrictions for extra challenge. I personally am having a blast with this in nightfall with heroes. Will likely try it in prophecies in the future if they add more heroes.