They had very little exposure in the mainstream gaming market and were overshadowed by AAA titles at the time. Vampire: The Masquerade - Bloodlines lost out to Half-Life 2 (or at least that's the claim), Arcanum lost out to the Baldur's Gate 2 expansion, Throne of Bhaal and the Gothic series lost out to Morrowind.
Of course, that doesn't necessarily mean that had those games not been released that those three titles would have been any more successful, but at the release of each, marketing was heavily inundated by adverts and press lapping up the AAA releases at the time.
People also criticised them heavily for being buggy and claims of being "unplayable" and "unfinished." Troika also had major problems with their publishers with both Vampire and Arcanum.
And the Gothic series was a little-known German-developed game that nobody cared about. Gothic 3 was their attempt at becoming more "casual" and to break through to that market and when that flopped, ArcaniA was made by a different developer (JoWood and Piranha Bytes had a falling out; Piranha Bytes went their own way, but made a deal with JoWood that allowed them to make one game in the Gothic universe while Piranha Bytes kept the intellectual property) and that was hugely casual and flopped big time. In fact, I believe it was the last "big" game JoWood published before they went bankrupt.
The thing is, all three of those games were "flops" to some extent, none of them sold well and many people bought into the bullshit that they were "bad" games and, at the time, they really did just appeal to a niche group of gamers. But they all became cult classics.
In that regard, Planescape is hard to ignore because it falls under precisely the same drama these games had. But I feel that series has somehow redeemed itself and became popular these days, whereas the others, I feel, are still kind of left "unplayed" and "unloved" and so I consider them underrated![]()
Arcanum is definitely underrated. If we were to open a poll for who has played it on these forums, I'd be surprised if that number exceeded 10% of the total forum members.
Another game I forgot to mention was the ever confusing BlazBlue fighting games. Weird story yes, but one of the more refined fighting games I've played. and on of the few to have genuine innovation in the mechanics.