dragonsweeper!

it's a browser-based pick-up-and-play minesweeper-like where you kill monsters in a dungeon, with the end goal being to beat the dragon in the middle of the board.
you advance by killing monsters hidden on the board, which do damage and give xp equal to their health. so you can only attack monsters at or below your current health. leveling up increases your health. open tiles show not how many monsters are hidden nearby, but their total health.

a good run takes around 7 minutes. getting a good run can take like 30.

Fields of Mistria.

I thought it was more or less of a Stardew Valley clone but with a little magic, and I mean that's technically correct, but it approaches a lot of little aspects differently enough to stand out on its own.

Something I've learned to appreciate is NPCs talk to each other, which adds a lot more character than having them give a one liner for the day.

And I got to admit, I like the fact you can swim and jump.

I recently played through Celeste and Birth :3 neither game is particularly underground or unknown as far as indies go though, so it's not the most interesting answer lol :3

I recently played Crow Country, an indie horror game very inspired by the look of old ps1 era Resident evil and Silent Hill. It's short, but I love how while the environments are fully 3D, they give that prerendered background look. You investigate a shut down theme park called crow country, looking for the man who owns the place. The narrative is pretty interesting but not anything groundbreaking.

Rebel Galaxy Outlaw - I needed to use a guide but I love the main character. I also really like that you can choose to be a space miner, merchant, smuggler, or fighter. The story was good, although I accidentally ended up not unlocking one of the companions so I missed a bit of it

Chrono Ark, a roguelike deckbuilder with some JRPG party-based mechanics and a bona fide full story visual novel built in. I finished it last week but have still yet to see the True Ending (not to mention 100% it, which will probably take 100+ hours if I decide to attempt to).

Game is fantastic, the gameplay is great and the boss fights are all super fun and interesting, each with unique mechanics and gimmicks. The presentation can also get pretty cinematic at times. Roguelike aspect is well made with tons of builds, lots of diversity run to run, synergies etc. There are optional bosses to attempt and an Expert mode with added/deepened mechanics for those who want a challenge (as well as a "Hope" mode for those who just want the story).

Finally, I actually really liked the story. Granted, I still have yet to see the true ending, but even so. The prose itself is not always perfect (partially due to translation), but if you can look past that I thought the plot was cool and it has some strong moments. Even as someone who isn't all that into anime it managed to land the important beats for me, which made me able to overlook some of the less than stellar parts (like the fairly tropey friendship mechanic). But even that was a little more nuanced than it appears at first.

Overall a wholehearted recommendation if you like roguelike deckbuilders.

I've been playing the shit out of Demon Tides.

Open-world 3D platformer with modern QoL mechanics, and customizable movesets/builds.

It's really good. I'm calling it a must-play if you like 3D platformers.