This is primarily for my players, but since it is tabletop RPG related, why not make it public?
1. Make all perception checks passive, made when next to a secret door or trap.
2. Eliminate inventory chips and tracking. Use consensus for absurdity control (I have 100 vials of alchemists fire, etc.)
3. Require treasure equal to treasure per encounter value, medium, in order to leave the dungeon. First person out with treasure equal to this total or more, wins. (This is an improvement, because it can allow for shorter, faster games). These tables can be found here under Building a Treasure Hoard. It's 800gp for 3rd, 1150 for 4th, 1550 for 5th
4. Organize treasure cards and monsters into 'levels' of treasure "1st level" will be CR 1/4 to CR 1 encounters and have treasure valued about 200 gp, 2nd level will be CR 1 to CR 2 encounters with treasure between 300gp. 3rd level will be CR 3 to CR 4 encounters with treasure around 400 gp. (or possibly adjust these treasure values (from slow to medium to fast) for the length of the desired game?) Technically, this could make a 1st or 2nd level starting PC a viable tactic to 'win'. (since they may only need 260 gp to reach their threshold). I would not really want anyone to start higher than 3rd level unless they win.
4a. Organize rooms into Rooms and Chambers. Rooms have 1 monster and treasure, Chambers have multiple monsters and treasure 1 level higher then the level of the area the chamber is located in.
5. Instead of random wandering monsters, have on released every 2 (?) rounds, and each time one is released it becomes more and more powerful.
6. Redesign the templates so that there are more hallways with adjacent rooms to avoid the 'wandering monster runs into a door' problem we had.
7. Still no idea what the winner should win.
8. Just in case it wasn't understood, You can respec your wealth by level every time you enter the arena.
In review over the monsters, excepting the rust monster, I don't think any of them were particularly hard. The DR was 10/Cold Iron, but you could just pay double GP (say 30 gp) for a cold iron longsword, and not had any problems. Going without alchemist's fire and cold iron/silver is just dangerous. I doubt it would have been an issue if we all weren't so rushed to make characters.
Also: You *can* trip in place of a melee attack. OH IF I HAD KNOWN THERE WOULD HAVE BEEN ANOTHER MURDER. ;-p Did you know if you fail your trip by 10 or more, you are knocked prone yourself? I did not until right now.