Diablo, which was recently released digitally for the first time on GOG, has now been joined by its non-canonical expansion, Hellfire. I confess I'd forgotten all about it, but enough people wanted to replay it that Blizzard has allowed GOG to throw it into Diablo. It's available as a free add-on for everyone who picks up base game.

Hellfire's not considered an official expansion by Blizzard. It was developed in 1997 by Synergistic Software and spun a yarn that took place alongside the original Diablo. It introduced the Monk class for the first time, along with a bunch of extra quests, weapons and monster-infested dungeons.

You'll face the demon Na-Krul, who has been unleashed on Tristram by a typically clueless sorcerer. To stop the demon from escaping, the sorcerer traps players inside its lair and tasks them with defeating it. Nobody cleans up their own messes in Tristram.

The expansion has been updated with high-resolution support and other compatibility tweaks to run on modern PCs. Diablo is also 10 percent off until June 17.