Some of the few i played the last year:

Tome 4: One of the best traditional rogue-like out there, with lots of classes and items. I won't lie, the graphics are dated but they grow on you. The greatest thing going for it, it's the number of races, classes, items that you can combine. You can play it for free on their page or get the paid steam version. It has some paid dlc. Sadly the developer hasn't appear in a while, i think they had a few real life problems, i hope they get better. Still the game is still top notch and with lots of content. If you are into traditional rogue-likes this one is a must play.

Cogmind: A traditional rogue like game but with a twist on the genre. Instead of exp, you get parts for your robot and part of the progression is learning about specific mechanics (info-war, stealth, hacking, etc). It has a really modern immersive ui, and really nice ASCII animations. It's tagged as early access but i consider it complete. It has dozens of different endings and ten years in development. But take my heed, It's pretty hard and may not be for everyone, some runs can be a bit frustrating. Check some videos or reviews before buying.

Caves of Qud: Lets keep rolling with traditional rogue-likes. This one is fresh out of the oven, I think they finished it last year and it was a fantastic ride. Unique setting in a post-apocalyptic world with mutants psychics and cyborgs. It has lots of customization, you can be a gunslinger mutant with 5 arms, each with a gun, four legs, two heads and that would be a normal run.Just so you get around the level or craziness the game has, you can have your face chop up by a conscious tree, pick it up and wear it over your already mangled face just to assert dominance (Really, the chopped face gives +1 EGO when equipped). Check it out, fantastic game.

Bonus track:

Song of Syx: A civilization builder, that plays like a mix of colony management and paradox grand strategy games. Great game with a great developer.

Dyson Sphere Program: Ok, this one may not be an indie game, not sure, it has way more developers than the other games. But they are great and the game is gorgeous. If you like Factorio like games this one should be your jam.

Non-Steam Game:

While not in steam if you have experience running things with wine and proton, I suggest giving it a chance, you won't regret it.

Star Sector: Space game where you explore the galaxy with an ever growing fleet. It seems to take inspiration on Star Control. The battles are fantastic, the effect when a ship goes booms it's glorious. It has a great community with lots of mods. It's still in development but i consider it already finished. It has enough content for hundred of hours and that's no even counting mods. There is a big update coming, I think at the end of the year, may be worth waiting for it.