Roguelites: The Binding of Isaac
Since I talked so much about Isaac as part of the primer, I think it's only fitting that this is the first roguelite I discuss more in-depth. Isaac is massive, spanning multiple expansions over a decade of development. This is both its biggest charm and biggest detriment, but I'll get into that in a bit. I'll talk about my history with the game first, then delve into some of the mechanics.
The Beginning of Isaac
I personally started playing all the way with the original flash version, picking up the expansion when it dropped. I played a total of around 60ish hours with the original flash version (compared to my over 200 hours with the remake), beat the game with just about every character and pretty thoroughly most of the content.
The flash version was, well, incredibly jank. Flash was not built for a game like this, with weird synergies and interactions and bugs and performance issues. It was charming in a way that games that really push the envelope are; you could see the core of what they were trying to do. Also it had Danny Baranowsky as the composer which they never quite managed to fill with the remake. Anyways.
I picked up the remake when it released a few years later and it immediately became a core part of my gaming rotation. There was always new items to unlock, new things to go for and also new expansions or item packs. That said, playing as The Lost on release was a way to quickly hate the game (since he had only one hit before death) and exposed many design issues with the game overall. They fixed it a year or so later with the Afterbirth expansion letting you unlock upgrades for The Lost that made it much less miserable.
So in total there was the Afterbirth, Afterbirth+, five 'booster packs' and Repentance which was a massive mod called Antibirth being made official. Antibirth was one of the few times I actually played (and donated to) a mod for a game I enjoyed, it was that good of a mod.
With each expansion though, the balance of the game started fraying apart. Which I think is the perfect jumping point into the actual design of the game.
Item Pools
Each item you unlock is added to specific pools. These include treasure rooms, shops, libraries, curse rooms, boss rooms, secret rooms, devil rooms, angel rooms, chests and a few more niche scenarios. Each item also has an associated weight to it, which indicates how likely that item is to drop when selected out of said pool. Isaac's item total, per expansion has gone from 341 -> 436 -> 547 -> 719.
For a brief second, I'd like you to consider what the problem might be. If you've played Isaac a lot you likely already know the answer.
Ready?
So what happens when you unlock a bad item? Not all items in Isaac are equally balanced (an impossibility); some items are so bad as to be worth actively avoiding. Every bad item you add to the item pool therefore dilutes the chance of you finding a good item. This became an issue in Afterbirth+ because there were a lot of new items that were joke-y, or detrimental or just plain worse than items that already existed.
Item pools and item weights is a pretty common technique nowadays for roguelite design however, so this isn't an exclusive issue to Isaac. Isaac just suffers the most thanks to the sheer amount and how long it's been around.
Though specific to Isaac was that some of these items were from challenges you could freely select from the main menu, which meant that a viable strategy was to simply just. Not do these challenges to avoid poisoning your pool. Metagaming the metagaming. And speaking of...
The Restart Button
The 'best' way to play now was to simply restart your run. You'd take a peek at the first treasure room, maybe play to the second floor, then restart if you didn't get a couple of early game accelerants. If you were a decent player and could take no damage for the early floors, then items that simply increased your health were actively detrimental to your play because they vastly slowed down each run.
It was a play pattern I myself ran into quite frequently because it was never really a matter of if I could complete a run, but how long it would take. And the time differential between a run with bad items vs a hot start and synergies could be a half hour or more.
Isaac never really solved this problem, or rather never really seemed to care. After all, it's the players choice if they want to restart for stronger runs or not. Other roguelites opted to solve this a couple of different ways, Slay the Spire gives you a stronger start if you at least play out a run beforehand for example. Ark's Wonder Dungeon has a particularly smart implementation of this, because you can carry forward an item from a prior run which'll appear at the last biome you won/died at. So you're always guaranteed at least one item you prefer, provided you play out the run.
Power, Uneven
The crux of the issue was also Isaac's greatest strength. When you had an insane run, it was insane. Synergies would let you obliterate entire rooms and bosses, become nearly immortal, fill up your resources and break the game. Conversely when you had a bad run, it was real bad. Bosses took forever, you got fewer upgrades because you took more damage and sometimes the game slaps you with multiple active items that you don't need.
For the base Isaac experience the power differential wasn't quite as wide, but powercreep tends to come for every game. Items became more powerful individually and also less common as the pool filled up with more items. It became such an issue that they introduced a much-maligned mechanic called 'boss armor' to many of the endgame bosses, which would cap how much damage you could in a certain time interval.
And...I don't really have a good solution to this problem. What they did over the course of many patches for Repentance is gradually tune the weights and buff some of the worst performing items while tapping some of the strongest ones. This might be the best compromise you can have.
On Snow and Balling
Still, one of the biggest issues remains, and that's how quickly player power compounds. Being able to snowball and have crazy runs is a hallmark of roguelites and randomization make no mistake. Where I think Isaac makes a particular misstep though is that it rewards you for doing so.
Isaac has two special room types: Devil Rooms and Angel Rooms. They both only appear after defeating bosses and only have a chance to appear. These rooms typically contain higher power items and are a great way to salvage an otherwise boring or bad run. They have a low chance of spawning, but if you take no damage for the entire floor they are guaranteed, and if you take no damage for the boss specifically they have a boosted chance. There are other criteria to make them appear such as bombing beggars or other specific actions; not taking damage is the most important for the sake of guaranteeing the room to appear however.
The paradox here is that people on a bad run will have a lower chance of encountering these rooms. Enemies and bosses take longer to defeat, which means higher odds of taking damage. If you're already snowballing, then encountering these rooms is easy and almost guaranteed to result in a broken run.
Most people probably won't care; at least not initially since you'll just play out the run. Later on when you're going for specific endgame routes or if you just want to be overpowered, these designs push you towards restarting early and often.
The Other Stuff
I focused a lot on items here because that's always been the core of my experience with Isaac. There's just, so much to it in general. You're not just unlocking new items with each character but also widen everything. You can unlock new pickups, new chest types, new arcade machines, rooms, endgame routes.
And speaking of poisoning the pool, you can unlock 'sticky nickels' which require a bomb to pick up. People really didn't like that one.. You also unlocked half soul hearts (which functioned as temporary hp) as a downgrade for soul hearts. It used to be something you unlocked for resetting 7 times in a row as their form of punishing that behavior. I think it was changed to be part of the 'everything is terrible' difficulty increase across the board
It's sort of weird to talk about since really, it's an attempt to increase the difficulty of the game by making drops worse. And while that feels bad from a player standpoint; it's not really fundamentally different from another aspect of the game. When you beat bosses enough times, you unlock the 'Everything is Terrible' achievement which makes the game overall harder with more difficult enemies and harder bosses and more frequent curses.
Oh and curses are awful. Probably one of the worst things in the game, just abysmal. No redeeming factor.