Some new things trying to kill you, some new items and abilities to help you, and some new ui stuff.
Some neat emergent gameplay is happening too. I punched an acid monster into a crowd of others. When the acid monster died it changed the nearby floors to acid pools that damaged everyone standing on them. They all died. Unfortunately for me, one was a summoner who spawns a bunch of creatures when it dies and another was an embigining monster that made the newly spawned enemies much harder. Then I died since I couldn’t run around them. Fun times.
The levels now have more creatures and a lot more gold and items scattered around. When you move over an item, you lose all your movement points, swap it with whatever is in that item slot, and a new enemy is spawned nearby. Ideally it becomes a risk/reward game of avoiding crappy stuff and deciding how many enemies you want to fight. You can try to grab all the good stuff and fight everyone off or make a run to the exit and maybe grab a few gold when it’s safe.