For me, probably Fire Emblem 4: Genealogy of the Holy War because it never got an official release in EFIGS.
::: My well thought out answer is at the bottom, but I typed out my stream of consciousness to get there if you're bored and want something to read (I clearly was... don't take my digs too seriously/personally, I don't actually care about game review ratings beyond the mind state and context of this thread :D )... :::
For something more recent, I'm going back through the Nintendo games that are rated low (not many) by critics, and the ones that are even moderately rated I haven't played, or only played briefly. I'm ignoring everything in the green (75 and up, I believe, because that amount is too high to be THAT overrated). https://www.metacritic.com/company/nintendo/
Wii Fit U has an average rating of 72%, and I mean that game is derivative of earlier Wii Fit games, but it's probably the game I got the most playtime out of on the Wii U besides Earthbound and Xenoblade Chronicles X. And I mean, it's not that underrated even by my reckoning. I'd have probably put it up in the 80s (for normal Nintendo users, not us typical forum users, many of us don't like moving at all).
There is also the Sketchpad app on Wii U, the one good app for the Gamepad, IMO. It has a 70, probably because it's software, not a game. But I found it surprisingly good for what it was and for its price, it was easier than your typical drawing tablet. To really get a better experience generally required a premium tablet + pen. So, I think that's a bit underrated, I recall it had a lot of great features. I actually forgot I gave that one a decent spin back in the day.
Fortune Street on Wii! This is a great family game. More or less a Dragon Quest take on monopoly. In Japan, this series went back 20 years prior to this, known as Itadaki Street; it was designed by Yuji Horii. The game got a 68, that is far too low IMO. Right now, that one is the most underrated IMO... especially when Skyward Sword sits right beside it with a 93, and I didn't really find that one all that interesting; I think I definitely got way more gameplay out of Fortune Street.
Disney's Epic Mickey sits at 73%, a little low, 10% under at least, IMO.
Super Mario Allstars, 70%. Was there any reason this one got so low? IMO, way under where it should be.
Animal Crossing City Folk, 73% is way underrated IMO. Again, if Skyward Sword is getting 93%, most Wii games are severely underrated.
Disaster Day of Crisis at 69% is underrated.
As a note, Smash Bros Brawl, I love this game, but at 93% I can't agree it's underrated, it seems to have wild success ratings-wise. And yes, you may see Melee fans say otherwise, but their opinions are meaningless; just like my opinion is meaningless when I say the N64 Smash Bros was the best one, because that was the first one I played, and didn't find anything special with the series again beyond the unique modes and characters (Subspace Emissary, Sonic, Cloud, Sephiroth, etc...), but 75% of my gameplay happened on the N64, it just happened that the game came out late on that console after most people had completely given up on it as anything more than a Goldeneye and wrestling game machine.
Endless Ocean at 72% is low IMO, this game was creative and quite well crafted for its time.
The Tower SP, 62% → A port of the classic Yoot Saito Yoot Tower/SimTower. I fucking loved this game, that's the new most underrated game I've seen thus far. I had to skim over perhaps 200+ Nintendo published games to get to that one. But for me that is a fantastic and classic game. Granted, it was a port of a 10 year old game, but this was one of my favourite PC games of the time on a handheld system. Also, one of the few sandbox games that had been on a handheld by that point.
Given the vast majority of Nintendo games are rated quite well, there isn't much to justify as being very underrated. A lot of reviewers did this game dirty. I will admit, it is a niche title, but when it comes to the gaming market, people don't generally look at everything equally, they look at the sort of game they want, and then they look at the score. It doesn't matter that Metroid Prime whatever gets a 99.8% or whatever when the vast majority of Nintendo fans outside the forum community bubble don't care about Metroid first person shooting games that lack multiplayer (or, if you want to get pretentious to make the game seem more special: "first person adventure" or it's an RPG because you play the role of Samus... and Japanese, a JRPG! Like Dragon Quest); bottom line, it'll make the niche audience more likely to buy it, but won't likely pique the interests of many who don't care about that niche. That means when reviewing a niche game, the proper reviewer is necessary for some kind of accuracy. the wrong audience reviewing it doesn't change the fact that the game is a lot better than a 62% for the people who would be buying this game. Me and like 6000 other people outside of Japan will be looking at this game, don't get reviewers who don't like these types of games... Yes we're a small niche, and luckily we already know the rep of the game and didn't give a shit about what they think when it comes to purchasing the game. But yes, for the purpose of this thread, these reviewers from 20 years ago are assholes for underrating this gem.
So: The Tower SP → final answer, Regis.
I describe myself as a little dose of toxic masculinity.
