I'm not even a Metroid fan, but this game actually physically disgusted me, and I want to kick Adam Malkovich in the balls until he turns to dust and then detach the part of the space station it happened in while it's in the gravitational range of a dying star.
Asset flip "games" that get sold on digital storefronts such as Steam, PS4 store, etc. They're not games nor are the people who make them actual developers. They're a jumble of pre-made assets or demo tools all combined into a Frankenstein's monster of a product and absolutely none of these are worth playing, much less, purchasing for any sort of fee. Some of these don't even have working executables.
Games that use greed and timers as their primary form of gameplay. Dungeon Keeper Mobile is one of the worst examples out there, not only having ridiculously long wait times just to develop one tile and the game coaxing you to spend money to speed it up, but it's a desecration of a beloved IP that hasn't seen an entry in years (in which the studio responsible for it was eventually shut down by studio killer EA). This also applies to premium 60 dollar games which have microtransactions and lootboxes in them, one of the worst examples being Call of Duty 4: Modern Warfare Remastered, also being a desecration of the original game.
Then you have the edgelord troll games like Ethnic Cleansing or Custer's Revenge, those which are made blatantly offensive just for attention (while in the former's case, is pretty much developed and published by Neo-Nazis). Weird how none of those games are good to play either, being ugly to look at and controlling really poorly.
And then you have games that are just plain out awful. People already mentioned this in the thread, but I'll mention them here. Games such as Action 52, E.T. (landfills galore), Sonic Boom: Rise of Lyric, Superman 64. We pretty much know these games.
There's also games that are entertaining in their awfulness to the point where it's hilarious to watch YouTubers play them, notable YouTubers being We Broke, or listening to Angry Joe rant about them. Examples do include Big Rigs, Ride to Hell Retribution (which also has edgelord shit in it), Kreed (Russian jank with phenomenally bad voice acting), The Quiet Man, Sonic '06...
And...games swamped in all sorts of controversy, such as the lootboxes in Star Wars Battlefront II having attention in mainstream news, Mass Effect 3's ending, SimCity's always on-DRM rendering it unplayable, the lies about Aliens: Colonial Marines, and just Anthem + Fallout 76 in general, all attributed to their "live service" BS.
I haven't even played any of these games and I thank god that I don't have to. Dealing with gacha in the free2play Dr. Mario World and CTR's microtransactions are already bad enough, and I can't believe it's only some of the milder shit compared to how bad games can really get. What is the game I dislike the most...Super Mario Galaxy 2? I wouldn't even call it a bad game. Pokemon Dash? It's actually just fairly mediocre. Mario Tennis Ultra Smash? It's main problem is that it's barebones more than anything else.
One of the worst games I remember is Block Party for Wii. Even for a kids game it is very terrible. I only got it because I when I was 8 I loved bowling games and there was bowling on the box art so I got it and... there wasn't even bowling! Also, it cost $20!!! I lost it but I kinda wish I hadn't just so I can see how bad it is again lol.
The worst game I actually own and have played for a decent amount of time is Seablade, a boring and pretty broken flight combat game exclusive to the OG Xbox. Basically the premise is that IN THE FUTURE the world is flooded blablabla global warming blablabla apocalypse and you pilot submersible fighter jet to fight evil warlords.
The problem is that the game is ridiculously repetitive: you have six environements and three types of misisons: "Recon" (pick up a series of blue markers until you loop back to the start", "Rescue" (collect a 6 to 20 civilians and drop them at your mothership) and "Boss Battles". There's only 6 recon missions and (iirc) 3 boss battles so the vast majority of the game is spent in these mind numbing rescue missions where you waddle in these empty open zones and fetch a bunch of immobile dudes (multiple times since all of the playable Seablades have a low carying capacity). There's no objective beyond that, no time limit, no change in the environement, etc etc. Needless to say, it gets mind-numbing fast.
There's other stuff like how the cutscenes beyond the opening are just slideshows (albeit ones with a ridiculous amount of different pictures) the control scheme has half the buttons mapped to reversing the function of the two analog sticks (????) and that the ability to go underwater is, despite what the title implies, barely a factor, but really, nothing can capture the Seablade experience better than playing it yourself.
The kindest thing I can say about it is that the voice acting isn't too bad and the horrible CGI slideshows can be kinda funny