Heroes of Might and Magic 3 is one that instantly comes to mind. It surprisingly still has a very active competitive playerbase, mostly comprised of slavs that have been playing it since they could read words on a computer screen. Another one that I've personally can't stop playing, is the first Warhammer 40K:Dawn of War game with it's expansions and mods. It's just so good, and I wish a modern version with a modern engine could be made. I don't trust Relic to do that tho.

Other than that, there's a myriad of old console and arcade games that are still excellent. Super Metroid, SEGA Rally, shmups like Dodonpachi and Mushihimesama, Street Fighter 3: 3rd Strike... there are really way too many to count.

Hybrid Heaven on N64. Great game with a super interesting battle mechanic. I've never played anything else quite like it. Maybe The Surge would be the closest system, wherein you can target specific body parts for interesting effects. But you can't suplex an alligator in The Surge.

My answer to that question is always "King of Dragon Pass", a narrative/management game that is unlike anything else out there. It got a spiritual successor with "Six Ages".

„Robinsons Requiem“, available on GoG.

It’s a survival horror first person rpg with a semi realistic health system. It’s creepy and hard and so goddamn good. I’m am actually surprised that it gets mentioned so rarely because I would not know of any other earlier game with those now so ubiquitous survival mechanics.

Star Trek Voyager: Elite Force.

• It's a first person shooter from a venerable studio in the genre, Raven Software.
• Put out during their "golden age", before Wolfenstein and Singularity flopped and uncle Bobby sent them to work in the Call of Duty mines.
• Really cool selection of sci-fi guns, some of them pretty unique.
• Campaign is essentially a prototype for Quake 4. It was built by the same internal team at Raven.
• It has a more interesting story than Quake 4.
• It's an early example of a game that lets you choose your sex. NPC dialog changes to reflect this.
• The whole cast of Star Trek: Voyager lends their voice talent to the game, including Jeri Ryan.

It also has a sequel, made by another studio. Elite Force II isn't quite as good, but it is still worth playing if you like the original. It loses the female protagonist option, likely because it was 2003 and the story had a love triangle. It's a visual powerhouse though, really pushing the limits of the Quake III engine far beyond what many people likely thought possible.

Out of This World and Flashback. Always favorite old school cult classics.

I'd heartily recommend Fallout 1, with a less enthusiastic recommendation for Fallout 2

Alpha Centauri. Just reading through all the wonder quotes and worldbuilding is amazing.

I've been playing retro games for the past years, and here's some that might fit the criteria of forgotten cult classics:

• ScummVM:
  • The Bizarre Adventures of Woodruff and the Schnibble of Azimuth: It's a funny and interesting point and click game, use a guide though, there are some obtuse puzzle and pixel hunting
• TurboGrafx CD:
  • J. B. Harold Murder Club: a straightforward but interesting crime mystery game
• SNES:
  • Ihatovo Monogatari: an interesting no combat top down adventure game
• Sega CD:
  • Snatcher
• Sega Saturn:
  • Policenauts: I like Policenauts more than Snatcher, but both are interesting sci-fi visual novel like by Kojima
• Playstation:
  • Mega Man Legends
  • Mega Man Legends 2: both MM Legends have heartwarming light hearted stories and okay gameplay
  • Tail Concerto: similar to MM Legends, but gameplay is bit more basic. Features tons of cute anthropomorphized cats and dogs. Very lighthearted
• Playstation Portable:
  • Remember11: The last game in Infinity series, co created by Kotaro Uchikoshi who went on and created Zero Escape trilogy. Out of the Infinity series, this is probably the best one, it is more sci-fi than romance/dating visual novel, there's no longwinded slice of life section.

All of those games are either in English or have been fan-translated

I’m probably alone in remembering this game but I loved Hardwar back in the day. It’s an Elite style trading game set on Titan. The player pilots a ‘moth’ ,a small flying craft, between craters.
It had an interesting story that played out as you explored with areas blocked out, due to events, and made accessible later on.

The developer closed doors but IIRC at least one member of the team released a patch that had been developed later on.

I played it pretty obsessively and it had a small passionate community but it wasn’t a hit.

i have a very specific genre of games that i absolutely adore and i'd suggest anyone interested take a look at them asap. the genre is japanese ps2 horror games, with standout titles being silent hill, fatal frame, haunting ground, rule of rose, and siren

Blade of Darkness. If you want to see the true origin of the soulslike genre, this is it. Be warned that the controls are extremely janky, though.

Quest for Glory 1 (called Hero's Quest at release) shaped my humor and gave me a lifetime love of fantasy in general, my username is the name of one of the minor characters. I recently spent a couple hundred dollars on a painting because it reminded me of Erana's Peace, a location in the game. Its sequels are great too.

BladeRunner rpg by Westwood studios is fantastic

I still believe Warzone 2100 is one of the finest RTS games ever made. It is also now free and open source.

https://wz2100.net/