From recent memory: Starfield.

I didn't think it was terrible in and of itself, but it also wasn't very good. It was just missing that certain something Bethesda RPGs had before it. Just a meh experience the whole way through.

Any assassin's creed from the last 10 years, probs gonna get hate for that but they are just so average to me.

Kingdoms of Amalur: Reckoning

Had all the individual makings of an exceptional game (with input from Todd Macfarlane, R A Salvatore and Grant Kirkhope), and while it was definitely enjoyable enough - it lacked any wow-factor whatsoever, winding up an otherwise forgettable 7/10.

This is probably more subjective than best/worst. So...

Vanilla Skyrim.

The outer worlds . it was just meh in my opinion. Not to be confused with the outer wilds game that I've yet to play

A hell of a lot of Ubisoft open-world slop released around and in the 2010s.

Starfield. It's the definition of a "mixed" rating on Steam. It's not bad, but it's not good either. You play it for an hour and your reward is that an hour has passed.

Anything from Ubisoft

This is a tough question because it's like asking "What's the most forgettable game you've ever played?" I can remember some of the best and worst games I've ever played, but mediocre games are explicitly not interesting.

That said, the first one that came to mind for me was Starshot: Space Circus Fever for N64. It's just a very generic late-'90s collectathon platformer. It's hard to be mad at it, because it's not terrible or anything, there's just no reason to play it. If you've got an N64, there's Mario, Banjo, Rayman, even B- and C-tier stuff like Gex and Chameleon Twist. There's hidden gems like Space Station Silicon Valley or Rocket: Robot on Wheels.

That last one is the only reason I played Starshot, I saw it clearanced at a used game store and was like "Oh yeah, I remember hearing this game was good," but it turned out I was thinking of Rocket. That game actually is good, while Starshot is just fine.

I think Halo Infinite qualifies, I played the multiplayer waaay back when it released so things may have drastically changed (haven't heard of it being the case);
it didn't / doesn't do anything that no other game does, nor did / does it do anything particularly well nor better than its competitors (including every Halo from Bungie).

I did watch a walkthrough of the campaign, and it doesn't look particularly engaging either.

From a gameplay perspective GTA has been mid for ages.

Pretty much every modern AAA game. Theres an exception here and there but really smaller studios have been making bangers that AAA studios just cant seem to touch

Ghost Wire: Tokyo.

It sells itself on cool aesthetics, but the moment you get past that you realise it's just a very, very generic open world shooter with incredibly bland and boring shooting layered over an impressively faithful recreation of Shinjuku. And even the aesthetics wear thin very quickly, being largely just a whole lot of "Hey I know that anime" level stuff cribbed from Japanese culture. The game is mostly just running around a map collecting stuff.

The Halo series.

I like shooters, so I got the full bundle and I tried hard to like it.

None of the games gave me a lasting impression. The plot didn't stick with me, the enemies were weird, the guns felt weak and flimsy, the rooms kept repeating in some sections and it got very boring. There were some fun bits with the vehicles, etc., but overall the experience was... pretty much average.

I was expecting something like the Half-Life series, but this wasn't it.

Square Enix games (FInal Fantasy, Neir Automata, Sleeping Dogs. Tomb Raiders)

They are all... good - certainly not bad games But nothing makes them... great

Probably everytbing put out by Nintendo in a long time. Yes, even that one. That one, too.

I said any Call of Duty from the past decade as answer to the original comment, and I still think that is a solid candidate. However, another game I played recently that qualifies I think is Sleeping Dogs. Perfectly cromulent 7/10 GTA clone but ultimately not pulling up any trees.

Dual nominations for Paper Mario: Sticker Star & Paper Mario: Color Splash. The only thing I really remember about them is that I played them and they left me without any feelings about them whatsoever.

Anything ubisoft makes. Or generally most things big companies make to cater biggest possible amount of people.

Neverwinter Nights

The multiplayer is supposedly incredible. But I remember being extremely whelmed by the main game.

But it's hard to remember the mid games. Because it is very likely that they didn't leave any lasting impression.

And especially if previous titles in a series or from a studio were great a mid game would feel disappointingly bad. Although compared to other games they might actually still be considered great.

Unreal 2, at launch, was the most absolutely 7/10 game I've ever played. Just a very generic singleplayer FPS, and not the sequel to Unreal that everyone was hoping for.

I say "at launch," though, because almost a year after the game's release, they added multiplayer, and that is still my favorite multiplayer game.

Mighty no 9.

Well, when it comes to video games, despite being foundational, Mario Bros. At the time, it was mids, but there were a lot less truly great games, and less abysmal ones so it looked better than it was. The series got better, but that first one was kinda meh. It's all timing jumps, which is fine as far it as it goes, but there were both better and worse options on that console.

Away from video game, Life is about as meh as it gets. No real strategy, no depth. But it's a good time killer and you can play it with a table full of people drinking and not get bogged down or into arguments because of the game (unlike monopoly lol).

Mechwarrior online.

Free, online "shooter", good community, runs on linux, gameplay is dated and doesnt get tons of dev support anymore but its still how I kill an evening once or twice a week.

Avowed was very mid. I enjoyed it enough, but nothing about it was particularly brilliant or terrible.

Greedfall

Godus.

I know lots of people hate it but taken in isolation it's okay. I found its aesthetics charming and its pace generally pretty chill. It wasn't good but it wasn't terrible. Low medium perhaps but I have comfortable memories of listening to an audiobook whilst playing it.