GOG.com is now selling a special version of Diablo that includes its Hellfire expansion at no additional cost.

Diablo fans can now play the unofficial update to the game in higher resolution with bug fixes and Windows 10 compatibility. The original Hellfire expansion was developed by Synergistic Software, not Blizzard, and was released in 1997. Blizzard has given GOG.com permission to include Hellfire as a free add-on for their sale of Diablo, after fans asked for it.

Hellfire adds a new, non-canon, single-player story where players fight to take on the demon Na-Krul. The expansion also adds a Monk class, as well as new items, dungeons, missions, and bad guys to take on.

Hellfire is the only expansion released for Diablo, with Blizzard never releasing an official expansion. The game was, however, sold as a bundle with Diablo in 1998.

Diablo with Hellfire is normally $9.99 on GOG.com but is on sale for 10 percent off until June 17 in the website’s Summer Sale Festival. This version is only available for Windows PC.