Why BioWare's Neverwinter Nights still has thousands of active players
The single-player is just OK, but according to the players, that doesn't matter.
Neverwinter Nights was made by the studio that produced seminal RPGs Baldur's Gate, Star Wars: Knights of the Old Republic, Mass Effect, and Dragon Age. It sold well and was critically acclaimed at launch. Yet, somehow, it has not been canonized in most gamers' minds over the decades the same way the games that came before and after it were.
Nonetheless, more than two decades later, it still has a tight-knit and surprisingly active community that none of those other games can rival. I think that's partly because it was a completely different beast.