I'm no paleontologist, but I'm fairly certain Tales of Maj'Eyal has been in development since the late roguozoic era, when dinosaurs roamed the Earth one tile at a time, and everyone ate lasers. Roguelikes seem more resistant to leave beta and declare themselves 'released' than any other genre I can think of, perhaps because they expect a sudden shanking upon emerging, blinking, into the overworld - not an unreasonable assumption, considering how many deaths they've been responsible for. And so it is that ToME leaves the beta dungeon and enters a, ahem, better one, leaving 1 million character deaths and 109 years of playtime in its wake . Man, someone shank it already.
ToME is one of the more major roguelikes available, with a fancy (optional) graphical front-end that my computer has never gotten along with for some reason. The game's open-source, and its T-Engine 4 is particularly mod-friendly, even if the user documentation is a bit sparse. It's one of the bigger, more complex roguelikes out there - you could probably get 109 years of play out of it all by yourself.
In truth, the game's 'release' status probably doesn't mean all that much - ToME will doubtless continue receiving regular updates - but it's a pleasure to see its ~14-year beta phase finally come to a close. Developer DarkGod isn't asking for any money for the game, but he is accepting donations to keep the project alive. You'll even get a few extra goodies by way of thanks.
[Thanks, Indie Statik! ]