Difficulty level is a feature introduced in the release version of Delver.
When Yithidian Orb is first retrieved from Yithidia, small orb symbol appear on the save file along with a number. Every subsequent time it is returned to the surface, this number increases. This number increases the difficulty of the game: the more times the orb was retrieved, the more difficult it will be to retrieve it once again.
There are various effects the difficulty has on the game. Some can be noticed right away when the orb is retrieved first time while others become apparent only several runs into the game. The effects include, but are not limited to (more testing required):
- Enemies deal more damage.
- Enemies have the more health, the deeper they are in the dungeon.
- Enemy spawn rate is increased.
- There are more enemies awaiting near ladders on the way down.
- There are more skeletons awaiting near ladders on the way up.
- There are more ghosts of enemies on the way up.
- On difficulty level 4 or higher, skeletons start spawning on the way up. It was initially that was on earlier versions of the game.
- Monsters start appearing on intermission levels.
- (Unconfirmed) Better items drop from monsters.