Some changes I'd make
- Portals have their spawn rate reduced drastically, along with drastically lowering the chance of a portal room appearing in the earlier floors, and ramping up more towards the end of the game. Portals make no thematic sense in the basement, but are perfect for later stages like Sheol and even fit somewhat into the Womb. Add a rare champion variant that has the original spawn rate.
- Remove mimic chests entirely or tie them to a trinket. An idea I saw on reddit was for a trinket that increases stats slightly, but also gives a chance to change chests into surprise spike chests. So there's a risk/reward system. Right now the chests just slow down the game because you need to approach every single chest in the game with care, which is really bad. Spike mimics just feel completely counter to the design of the game. The series already has a "lel trollololo" chest, and it's putting troll bombs into chests. Why is there yet another layer of punishment?
- There are item rooms with poop instead of items. What in the world?
- Drastically reduce the HP of Big Horn and the Sisters Vis. It's absurd the HP they have.
- Add an animation "tell" to the Sisters so you know which attack they're going to use. It's just poor boss design to not have any sort of warning in place for what attack they're going to use, especially when they're dodged in completely different ways.
- Get rid of every single Lost run ending rooms. 7 Blasts, Drowned Leech Brownie. Those things have no place in the game at all and do not add anything to the game besides "lel you died due to a random room being unbeatable with your character" Every single room in the game should be tested with Lost to ensure it's actually possible to beat with that character. These stages and bosses just don't feel play tested at all.
- lol Greedier mode. This almost seems designed out of spite. "You didn't think Greed Mode was fun? OKAY HOW ABOUT NOW!"
Things that are good/great and don't need to change
- The Mushroom enemies are quite frankly the best new enemy. Simple in design, has RNG elements, but isn't unfair.
- The rock Fatties. Yea... I actually don't mind these. They're kind of annoying, but not really terrible. A little too common maybe. I think they're fine.
- All of the new items are fantastic. I think like 75% of the effort went into making the mod tools, 20% went into new items, and 4% on the new challenges and 1% got the rest of the effort, and it shows.
- The new character is great. Super overpowered if used right, but if used poorly is terrible. Don't suck up a D6 or D8, kids.
- The new challenges are great. Pong was the single most powerful I have ever felt in Isaac. Brim + Guppy + Tammy's Head, I was unstoppable.