The
Styx games. They deserve a lot more attention than they've ever gotten, especially within the stealth genre seeing as it's such an anorexic genre with not much outside of Metal Gear, Splinter Cell, Thief and Hitman as primarily stealth focused games
(with Hitman being the only one that's actually still going at this point). Otherwise we just get games where it's either an bare bones option and/or just not done well at all, such as Assassins Creed or 'open world Bethesda games'.
And you get to play as a Goblin. Not enough games let you be a Gobbo.
Dragon's Dogma was brilliant, but never really had a chance to shine with Skyrim coming out at the same time and taking the limelight, being seen as an 'inferior Skyrim' despite being nothing like it
("but it's got dragons and swords, obvious rip off"...). Loved the mix of Monster Hunter and Shadow of the Colossus with classic aRPG elements, fighting mythical beasts like the Hydra and Griffin, and it had pretty damn good character creation too...Not many games give mechanics where your characters height and weight make a difference.
Shame it never really took off. Japan got Dragons Dogma online, but outside of that I highly doubt there's enough interest for a sequel given its been over 6 years with not a single mention at the possibility, some DLC and a rushed remaster nobody bought being about it.
Brutal Legend. The gameplay mechanics basic with the RTS elements being wonky and unexpected
(literally no mention it was part RTS until release...), but as a game inspired by metal music, there's really nothing that comes close to being such a fangasm for a genre as this.
Skies of Arcadia, Beyond Good and Evil, and Psychonauts all immediately come to mind.
Maybe at one time, but I would argue Beyond Good and Evil and Psychonauts have crossed into the territory of being kinda a bit overrated at this point. They appear in basically 95% of 'underrated games' conversations, ironically making them the complete opposite...Which is most likely why they're getting sequels, since not many publishers are going to push out a sequel to a game that isn't popular, especially Ubisoft who seems to be pumping a lot of money into a sequel of a game that was "underrated".
Skies of Arcadia I'll agree with though. They appear in a lot of Dreamcast and Gamecube related topics, but outside of that I never hear of it at all. Doesn't help that SEGA barely want to do anything outside of Sonic, Yakuza and Hatsune Miku games, or they could throw a port of this somewhere.