Fun fact: some mechanics never came back cause they got copyrighted and the studio with the copyright went "no, we're not doing that kind of game anymore" and as soon as anyone goes "okay, can we try?" they sue them into oblivion for copyright infringement

Tf2 nemesis System in pvp shooters

Did you know Shadows of Mordor copyrighted the Nemesis System and then proceeded to never use it in any other games ever again despite people calling out for it?

That's one I'd like to see

I really want to see a god game with gestures, like black&white, make the jump to VR

NFL 2K5 gameplay in a newer football game

Magicka 2 combat in some 3rd/1st person action RPG

The scrolling health bar in Eartbound/Mother

Vehicle combat games. Which I guess is more like a genre than a mechanic.

Right now it's basically Mariokart or nothing.

Grip came out in 2018, but the physics were really unforgiving (clipping a corner could cost you like 10 seconds as you tumble) and there weren't enough players online.
Which is a real shame because it's gorgeous, fast paced, with effective power ups, and amazing tracks. And a hell of a sound track.

randomization of stats, on weapons and gear. i feel like that adds interesting elements, diablo 2 for example.

Trade Runs from silkroad online.

Take a look at Half-Life 2's old Face Poser software. I feel like you don't see that sort of action-level control much anymore.

Indie studios are evading the need for lipsync entirely, by making simple models, giving people masks, putting them on radio overlays, etc. AAA studios are overengineering it, putting a $4,000,000 actor in a motion capture suit for each of their cutscenes to capture every fine detail as they stare in wonder at the white ping-pong ball in the studio with the sign written; "LOOK HERE".

Face Poser was a good median; it's where the director gets control, but you don't need a vast technical setup beyond animations, some vowel extraction, and some basic know-how. It means that if the director wants to add a criticism "No, character B should give a dubious, unsure look when character A says that", it's something they can apply directly rather than ask the animators to do by hand.

For some reference, old machinima like Clear Skies, or my own "AS" made use of Face Poser.

Destructible environments like in silent storm. You could remove walls and floors with grenades or mines. Unfortunately it was a bit buggy and slow. Teardown is fun, but it feels like a tech demo.

I miss casual flight sims that were designed to be played with a joystick. Not so much Janes F-15 1997 or whatever, i'm more talking about Crimson Skies. I want more Crimson Skies.

• an absence of quick-time events (I hate those things in cut-scenes, parry systems, etc.)
• a mode that allows the player to destroy the environment, NPCs, etc. including, when on, making the game unable to be completed potentially. I think having that be a toggle will still allow people to relive older RPGs where you could easily ruin your life without knowing for hours.
• Off-the-wall weapons. I think Blood 2 had a few and even halflife 2
• Counting beyond 2, speaking of the above.

Mods and self hosted servers

The instant i read farcry 2 i thought of the fire too.

The fire was amazing and gave me interesting ways to burn out enemies in outposts etc.