Roguelikes with the potential for broken builds.
Sometimes you find the perfect combo on your run and become an unstoppable force, but it doesn't ruin the game because you finish your god-like run and next run you try to find another overpowered build.

I do enjoy game mechanics that interact in emergent ways that weren't fully planned out by the developer in games like Dwarf Fortress.

I like most game mechanics to some extent. Creativity in combining game mechanics is key to making an outstanding game imo.

However, I don’t like things that force a time limit. I play games as an escape. I don’t like feeling stressed by a clock while I’m off the clock. These can be literal timed missions or things like a food/water meter. Escort missions also suck for similar reasons.

I think difficulty in a game should come from overcoming a foe, traversing harsh terrain, or solving a puzzle. If the game is hard because I have to stop what I’m doing to feed myself, or I have to rush to complete an objective on a timer, it just becomes work.

I'm not that excited by deep skill trees or crafting or inventory management, lately i enjoy good movement, music, exploration, and story.

The movement in destiny 2 felt really good, similar games have it where you get momentum, dives, floating with warlock, etc. I think Titanfall 2 and borderlands 3 zane had similar really good feeling movement.

The exploration in pre planes EverQuest was great, fast travel limited to certain classes and levels, risky but faster travel routes in kunark, groups in overworld and dungeon areas, dangerous places to get to with high reward for the risk. Elder scrolls, dark souls/elden ring, and Zelda breath of the wild had similar feelings for me.

All the stuff mentioned here with jiggle physics

I'm not sure if this counts as gameplay mechanics or rather narrative structure, but games like Outer Wilds, Fez, Tunic, where the exploration and discovery of the game is the end goal of playing the game, not just getting to the game's end state.

I'm not sure if there's an accepted term for these games, but I've always thought of them as "archaeology" games. There's a bunch of stuff, both plot and gameplay, that is hidden (sometimes in plain sight), until you discover it and find out what meaning it carries.

Peaceful exploration

Inventory Tetris

Among plenty of the other things mentioned, I enjoy “diagetic interfaces”. Ways of interacting with a game’s systems that stay grounded in the reality of the setting of the world. Dead Space is a prime example, but I’ve been enjoying a lot of the crafting in Vintage Story for this reason. The smithing in particular has had me hooked for a while. Hammering out my armor and weapons voxel by voxel made finally suiting up and feeling ready to take on a boss that much more satisfying.

Parry and riposte mechanics make me happy. Idk why exactly, but something about timing a parry and making the enemy entirely helpless for the followup is just great.

Save anywhere

Roguelikes and roguelites tend to be my favorite. Ones where each run is new and you can toy with different builds and usually get pretty OP toward the end (or get cut down early because luck wasn't in your favor or you made a mistake).

I like systems that allow for outrageous combos, whether unintentionally or by design. Roguelikes and roguelites usually have them, but it's almost entirely luck based. Dynasty Warriors 8 allows for plenty of OP combos if you manage the right weapon attributes. Skyrim and its ~~broken as fuck~~ perfectly balanced enchanting + alchemy (or Morrowind's even more perfectly balanced permanent fortify attribute magic)

I love anything with a tech tree or a skill tree or items that improve based on usage. The ratchet and clank games have such a great mix of all of those things, I end up spending a bunch of time just leveling up the guns!

I really like Zelda and Ys style ARPGs. Specifically, rare and impactful loot, and little reliance on skill levels, but rather skill aquisition. Both approach it very differently, and later Ys games fall into more traditional RPG mechanics (e.g. farm money/exp, buy gear, etc), so I'm more talking about Ys 1, 2, and Origin, as well as pre-BOTW Zelda games.

Basically, I love this gameplay loop:

1. Enter dungeon/level and fight baddies
2. Find important item/ability
3. Use important item/ability to defeat monsters
4. Fight boss, using a mix of important item and learning movesets
5. Repeat 1-4 several times, with plot mixed in
6. Fight final boss using a mix of everything acquired

Ys and Zelda do this in very different ways, and I absolutely love the level cap in Ys 1 to enforce playing smarter instead of grinding. You can never really get OP, even if you try (except Ys 2, which I don't like much).

Unfortunately, "ARPG" has been twisted to mean Diablo-like, which is heavy on loot and ability trees instead of puzzles and exploration, and future Ys games go that direction as well.

This isn't really specific to mechanics or systems, but I'll like pretty much any mechanic or system that lends itself well to that gameplay loop.

Enemy ai that's not stupid

I don't know the name of it, but I really enjoy the sort of gameplay where you roll up to an enemy compound or something, and then you just sort of chip away at it and cause chaos until it all falls apart.

The sort of thing you'd do in Farcry, where you'd snipe some dudes, plant traps, shoot the tiger cage so the tiger would get out and eat people etc.

Puzzles, traditional or unique, as well as physics and spatial-heavy thinking.

I really like the resource/inventory systems of survival horror games. Often they can force interesting decisions as long as your current state doesn’t starve you of options.

• I can’t pick up shit! Well, I’m not using these three things so maybe I should box them. Or, I could use up some ammo on nearby enemies.
• I’m low on healing items! But I have a lot of ammo. Maybe I could stop conserving nuke launcher rounds to trivialize the next few rooms of giant zombies; try a bit more of this other weapon I don’t use much and stow my normal pistol.
• I’m low on ammo! But, I’ve been saving a hundred healing items. Maybe I can practice tanking past enemies and see just how much it will affect me.
• I’m okay on ammo but these enemies keep coming. But…I think if I make it to this area, it will give me a stationary healing spot. So I’ll just conserve ammo and take hits on the way.
• I’ve been poisoned! But there’s gonna be a bunch of other poisonous enemies before I get through this area. Maybe I can ignore it until I’m through.

I think I’d even like to find more games that focus on that sort of item management without being so horror-focused; helping you feel excited for saving an inventory spot or prioritizing the right things. It’s especially cool when you’re finding ways to shift risk in the right directions based on what you can afford losing. Example in Back 4 Blood: There are tools/resources that retain/add more “possible downs” for a survivor, which may mean you can put off healing for a long time and keep picking each other off the floor. One game has a death prevention item that you can only hold one of; so you’re encouraged to “get killed” before you find another one.

More floaty, less realistic platforming. Thugs like double jump, or somehow your character has less gravity when they jump, stuff like that. Stuff like that. As a general platformer lover, I really enjoy more fictional cannot be done IRL physics in games.

Survival mechanics like S.T.A.L.K.E.R and New Vegas, dont give a damn for building mechanics though unless its simplified down to a simple upgrade system like Skyrim Hearthsfire DLC.

Games with high mobility mechanics like titanfall, echo point nova, doom eternal, destiny 2 strand hunters.

I really REALLY enjoy boss invulnerability phases.

Not a game mechanics maybe but more of an engine thing i guess. I just love simulations. Good VR combat physics, elemental stuff like water, fire, smoke, crumbling stuff. I love a world that feels dynamic but not necessarily realistic that makes sense of itself.

The controls for the Skate games, especially 3, are great.

It's easier to say what I don't like. Open worlds and crafting mechanics, they are just so boring

I love fluid movement. Doing things in a state machine is usually the way to go in 2d platformers, which is what I mainly make. I like when your character can move around without issue, so double jump, sliding, rolling, attacking etc.

Intricate character building with multi-class synergies. Is. My. Shiiiiiit!

Small wonder I love BG3 and Owlcat's Pathfinder games.

You know what I miss? The Ultimate Alliance games from the PS2 era. Isometric view. Build a four-person team of Marvel characters. Some team combinations grant group buffs, like having all four members of the Fantastic Four will increase your XP gain. Equip your characters. Pick from an array of comic canon costumes, each with their own abilities. Some combinations of equipment or costumes will also grant bonuses like having everyone wear their Age of Apocalypse costume.

The whole thing is an action RPG where you play through some big comic book crisis. Lots of opportunity for villain and hero interaction. Cool cinematics.

It's a rock-solid platform, but I don't feel like I see it used nearly enough. I remember playing an Ultimate Alliance on 360 and it just wasn't as good; smaller roster, fewer costumes, less interesting in general, despite the better graphics.

I vaguely recall hearing something about one on the Switch and that Midnight Sons was a bit similar... but then again I don't recall hearing much else about those games except for their existence, so they can't have done very well.

I'm an absolute sucker for a hidden traitor mechanic. Boardgames like Battlestar Galactica, Werewolf, and Secret Hitler (the latter of which might be my absolute favourite board game). More recently I've just started playing Among Us (I never got into it during its ~2020 peak) which is the first time I've seen the hidden traitor translated well into video games (unless you count that one minigame from Jackbox Games).

I've only realized it recently that I'm obsessed with simulator games. Eurot Truck Simulator 2, Software Inc, Minecraft? Rollercoaster Tycoon, etc.

Detailed completionist checklists.

If I have cleared an area, I want to have it reflected in an overview screen.

If I'm missing an item, I want to know which enemy drops it, where I can find it, or how I can craft it.

If I need to pull out my phone to check a wiki, then the game has failed me.

There's something to be said for exploration games, and in those cases, the details should be obscured until the player has cleared 90% of the area, or gotten past the boss (or something like this).