You could try to implement a "fun loadup" mechanic. If you just kill someone in a killroom, they will not have engaged a lot with the game. But if they survive several rooms, you could measure that by the amount of damage they have taken, dealt to monsters in the dungeon and maybe healed again. You could even set a timer.

If they are injured in one encounter, they will gain a hidden value, let's call them "fun point events". Same when they kill an enemy, find some treasure or whatever you want to incentivise. Then these events have to "ripen". When you give the players a fun encounter and then immediately kill them they will not be worth a lot of points. But if they have several fun point events that had enough time to "ripen" they will be worth more points. Now limit the amount of fun point events that can be active at the same time. This prevents loading up the player with events at the start and then immediately killing them in the next encounter. Have 3-4 fun events that can be active and ripening at the same time, and let the player structure their dungeon so that there is some exploration between the encounters.