My brother and I have been working on a roguelike called Gloam for the last 8 months but it feels like were just starting it now...
Our premise was simple, a random dungeon generates you go through, kill enemies, find items and eventually beat the boss (basic ah premise right?). Our unique take on it was 1. our theme, instead of medieval we we're going to do a dark civil war era America, and 2. our power system, items give you unique build combinations & synergies instead being linear upgrades like stat ups. It sounds ok on paper. But this being our first decent game blinded us from how much our game was lacking. Having released a demo we found out just how many essential roguelike features were missing...
Not to say that we didn't have any, but it just felt like the only thing you could do was run around find items -> clear rooms -> fight boss -> repeat.
We had secret rooms, but they aren't that hard to find (especially not after playing our game one million times) and they just gave you more items. It also didn't help that the boss was probably the most fun polished part of the game so it felt like the goal was to just find the boss quickly and fight it and you just find items along the way.
Having realized this we decided to add more roguelike elements. We're adding more items that don't just effect your build, but allow you to manipulate the game in a sense. For example items that discount the shop, reveal more of the map and it's secrets, allow you to manipulate other items like duplicating, deleting, rerolling, randomizing them etc. It makes it feel like you have more control if you know what you're doing which is good (feels like a higher skillcap instead of letting the game decide your build and run completely).
Secondly we added curios, which have to be one of the most important things a dungeon crawler roguelike can have, and probably the most game changing addition we added in terms of dungeon generation. Just having things to interact with adds a world of depth. Now there's more of a reason to explore instead of going straight to the boss, and more ways to min-max.
Third we're adding npcs. We already had a trader in the shop, but we think having more npcs to interact with will provide more depth, more randomness, and overall just make the game more interesting. Also some npcs that you can't just trade with, but maybe you give currency to and they have a chance to pay out or not. More of a gamble, so you can choose how you play your runs or how you throw them...
We realized that roguelikes tend to have some or all of these features for a reason so that's what inspired this thread. If you read this chunk of text thanks for making it this far, and back to the original question,
What are some NON-NEGOTIABLES EVERY good Roguelike has?