Gaming

Don't sure if it's exactly hidden but for me Dungeons III (and 2) has been unexpectedly fun. It takes everything that made Dungeon Keeper and it takes a level higher. Pretty fun game.

-Super Kiwi 64

Retro 3D platformer in the vein of Banjo Kazooie.

I enjoyed atomicrops tremendously

recently got completely addicted to a text-based Indie RPG called Roadwarden. The story and characters are incredibly rich and the gameplay is full of satisfying little moments of "oh, I have just the item for this!" or "another character told me this tavern keep doesn't appreciate jokes; I better get straight to business". I haven't beaten it yet, but I can't wait to see where it leads!

Ring Runner: Flight of the Sages is a 2D top-down space shooter with RPG text-adventure elements outside of the combat scenarios. I found it a super fun game with an insane amount of content. Probably over a hundred hours worth. There's a bunch of weapon and defense customization when it comes to combat, and there's probably thousands of varieties of ship you can build for whatever duty you need it to do.d

I believe if you play with a controller it has twin-stick controls, but on PC the controls are more like Elite: Dangerous or No Man's Sky, just in a 2D environment.

Narita Boy is a really cool glitch aesthetic sidescroller

Owlboy was better than I expected it to be.

Sayonara Wild Hearts is an absolute gem. Perhaps not "hidden" since it did get a full physical release, but I don't see people talk about it. Game is like an hour long but it's absolutely worth playing. The portal of music games really.

Also shoutout to selfy collection. idk if it counts as indie but it's low budget for sure, digital-only release, and filled with engrish, but it's a lovely game and easily the best dress up game on switch.

It's admittedly gotten a lot of shout outs with Diablo's release, but Grim Dawn. Just a super great old school ARPG with a fun multi class system. I think I made a mistake by letting it be one of the first in the genre I really got into, so it's kinda tough to find another one that competes.

Kenshi - a brutal, and sometimes janky squad free roaming game. I have far too many hours in that.
Pulsar - Lost Colony - Fun game if you have a few friends around. Pretend to be Captain Kirk - except chaos.
Rimworld -- Dwarf Fortress lite
Dwarf Fortress - Grand daddy inspiration for most other games
Torchlight - Diablo
Project Zomboid - All your top down zombie hunting dreams come true
Carrier Command - Drone carrier warfare
Nebulous Fleet Command - The Expanse.

Does X4 count as Indie?

One of my favorites over the past few years is Prey(2017) it was made under Bethesda so I wouldn’t say it’s underground, but It didn’t get the popularity and fan base it deserves. Essentially a open world (as open as a world can be in a giant space ship) that allows you to explore and fight creepy creatures. It also gives you multiple ways to solve the problems you face as well as Multiple endings and story branches to choose from. I played for 33 hours and it was so worth the price it was on sale, (wish I could remember) but it would also be worth $60 as well. It reminds me of a high polished Skyrim at certain points. Would highly recommend

Superflight

Really engaging game with a short, easy to understand mechanic. It's fun just to put on and fly around for a bit every now and then.

Lost Pig And Place Under Ground

An old-fashioned text adventure, one of the best ones I've played.

Pig lost! Boss say that it Grunk fault. Say Grunk forget about closing gate. Maybe boss right. Grunk not remember forgetting, but maybe Grunk just forget. Boss say Grunk go find pig, bring it back. Him say, if Grunk not bring back pig, not bring back Grunk either. Grunk like working at pig farm, so now Grunk need find pig.

Check it out

I really enjoyed Songs of Syx. It's a city builder and economy game, but with a lot of extra detail that you don't often see.

Some games I recommend:

Alina of the Arena: A roguelike deckbuilder game. It has turn based tactical battles. There are lots of cards and builds you can try, but there is a fair amount of randomness to it. So you have to go with what you get.

Unreal Life: A really strange, surreal adventure game with a talking traffic light. Great visuals and music.

YumeCore: Just a short little game where you beat up people in a hospital. Why? Why not?

Flood of Light: Great little game with pretty much one core mechanic (direct lights). The Engliah translation isn't the best, but I really liked the atmosphere.

Brotato: Is it a hidden gem? I don't really know, but it is a fun "Vampire Survivor"-like game and a huge time sink. Great shop mechanic and large amount of characters and items.

Gunpoint

S.P.A.Z.

Eufloria

Astroneer

Manifold Garden

Massive Chalice

The Pedestrian

Solar 2

Snakepass

Stacking

I’ll say CrossCode. 2D hack-and-slash set in a futuristic MMO. Way too good, way too unknown for the genre that it is.

As a big metroidvania fan, I'd like to introduce a few of my favorites that go beyond the obvious choices like Hollow Knight and Ori (which of course are excellent). All of these are straightforward and while difficult, they don't focus on confusing menus or min/maxing statistics.

Astalon: Tears of the Earth: If you play one game on this list, play this one. You play as 3 characters, each with their own abilities, and can switch at certain save points. You die a lot and have to start over from the entrance every time, but the game gives you plenty of shortcuts and upgrades that you can quickly go back to where you were. The map is great to explore and there's a lot of content to keep you busy like a boss rush and new game+ modes with different characters.

Momodora: Reverie Under the Moonlight is a short but sweet experience. It's difficult but not unfair enough that you want to stop playing, the world map is well designed, and the pixel art is great.

Rabi-Ribi: This game looks like it was made for a very specific (horny) crowd, but there's a surprising amount of depth to the world and the bullet hell boss girls that inhabit it. It's an interesting mix of bullet hell and platformer that somehow makes up for the nonsensical story.

Ooh, I love finding obscure indies. There are an awful lot of games on Steam and Itch and other platforms that are amazing experiences, but that almost no one has ever played or even heard of for one reason or another.

One of my recent favourite zero-budget indies is Sally Can't Sleep, a strange first person platformer with a lot of focus on fun, versatile, and exploitable movement mechanics. The dev sacrificed visual polish for quantity and style, so the game has a lot of interconnected levels with a big variety of different mechanics and visual styles - it's a really good example of how much a solo developer can accomplish.

Another one is Worlds, which is a 3D stealth-shooter-platformer-adventure? I like it for the same reason as Sally Can't Sleep, it's ambitious and creative, and you can really feel the developer pushing against their limitations to release something that punches far above its own weight.

Also, both these games are very cheap, even at full price!

eastward: topdown-zelda like. gameplay wise, though it's quite easy. the story is charming, with all the quirkiness from earthbound, although the main plot is actually more akin to the last of us 1, for some reason, or at least it kinda felt like that to me. the visuals are absolutely gorgeous, as is the soundtrack.

phoenotopia awakening: an action rpg-metroidvania mishmash, and a surprisingly large one at that. if you're into challenging and backtrack heavy games, this one does the job very well.

crosscode: this one's been mentioned a bunch on this thread, and there's also been a post here about it a day or two ago, but i'll still mention it because it's just that good. another topdown-zelda like, but keep in mind that i've seen it described as a puzzle game masquerading as an rpg, which may be a more apt description.