Marvel's Midnight Suns. It wasn't a huge flop, but not successful enough to get a sequel, which makes me very sad. I think it failed because it had a useless ingame shop, which made the game look like another cashgrab, when in reality those who bought the Legendary Edition have every skin included. Legendary edition has often been on sale for 50€ and that's definitely worth it. I enjoyed the game a lot and both the base game and DLC offer great characters that are both fun to talk and to play with.

Avent rising. They should have had a sequel but I know it would have likely just gotten botched and I would have hated playing it.

Fuga: Melodies of Steel. A pretty interesting JRPG+resource management game about animal kids in a giant tank from a lost civilization, fighting in a war to save their families.

CyberConnect2 has been making games for this setting since the PS1, though the previous games were more of 3D puzzle actiion games. But these games never sell as much as they deserve, Their commitment is amazing to keep trying anyway.

Fly'n, it's a brilliant platformer from like ten years ago https://www.youtube.com/watch?v=2UECUVRWpFM

Project x Zone 1 and 2

Probably my favorite crossovers in video games besides smash ultimate

Vintage story

Offworld trading company was an amazing PvP game but "economics" never was gonna sell.

The Dream Machine.

A Robot Named Fight! https://www.arobotnamedfight.com/

"A Robot Named Fight is a Metroidvania roguelike focused on exploration and item collection. Explore a different, procedurally-generated labyrinth each time you play and discover randomized power-ups to traverse obstacles, find secrets and explode meat beasts."

It's such a good game, almost everything is perfect IMO, I have over 200 hours in it and still go back to it every now and then. The lone developer also made the source code public a while ago, so there are mods, forks, spinoffs etc. being worked on.

I've been interested in Soulslike games and got Code Vein on sale recently. I think I'm about halfway through and it's pretty good. Playing at the 2nd hardest difficulty, dying here and there but also one or two shotting most bosses, which suggests it's found a good sweet spot for difficulty where it's not overly punishing but also not trivial, though I kinda wish I had started it on the hardest difficulty. I'm not sure how popular the game was but I suggest it.

Are visual novels allowed? If they are I strongly recommend you:

Hotel Dusk and its sequel, Last Window. Time Hollow.

All these three games are for the Nintendo DS.

Everhood is really unique and id recommend it to anyone who enjoys Undertale.

I also want to shout out just shapes and beats which is a good time and I pray it'll see a sequel