A total conversion of Troika's 'The Temple of Elemental Evil' for the classic D&D module 'The Keep on the Borderlands.'
The Circle of Eight modpack for Temple of Elemental Evil turns a game that's flawed, but still playable into a generally fixed game plus a free fan expansion. (Speaking as the designer and voice actor of Ronald Rynnwrathi, Cleric NPC of Saint Cuthbert, I'm biased in that regard.)
Note that 10/10 is not 100% perfect on my grading scale. It just means this is the best version of Temple of Elemental Evil available. The fact that this modpack is still being worked on by dedicated folks like Shiningted of Co8.org makes it a 10/10 given the context.
The low spoiler version is that this modpack includes new NPCs, new locations, new quests, new spells, new items, and more bug fixes than I can count! Just go play using the Co8 modpack if you have any ambition to play this game at all! I recommend the New Content version to see what's available!