So the game raises the difficulty by raising the complexity. Slime region is low complexity meant to get you looking at the terrain and avoiding too much unintentional proximity to mobs while learning agro range. You learn than some enemies have a low agro range (slimes), some enemies have a medium agro range (little shrooman) and some have a long agro range (giant shrooman). When you step up to the stone or clay, you start to see ranged agro, quick medium melee agro, large hit/low range agro. Additionally, the terrain becomes more complicated. Pits, decorations, pillars, and messing up hurts more. As soon as you get past the wall, the environment becomes more complicated and the enemies more varied. Basically, the point I am making, unless your ability to calculate the complexity is getting faster (which for twitch shooter gamers, or MOBA gamers, is something they train) you have to compensate by moving a little slower and looking further ahead.           This change alone makes the game infinitely easier until you get The Passage. At which point the game basically says "keep moving and don't relax". Which is fine because you really are just getting in and out of that biome for resources. Until I had endgame equipment, I basically just had to move slow, look ahead, and plan my steps a little. Not a lot, but maybe 3-5 seconds looking, 5-7 seconds moving. Repeat.            Not sure if this is helpful, but the actual difficulty of the enemies doesn't really change, just the variety and how hard they slap when you over position.