Jehuti is a specialized game engine and editor built around our idea for a discourse-based gameplay.
It is not released yet (because unsupported and undocumented) but you can mail us for the sources or find them easily in the Atelier, at your own risks. It is written entirely in Python with the SDL-based framework pygame, and fully open source.
We'd like people to mod our games, contribute maps and stories in the Atelier, create - and why not sell - other games based on our idea or refining it, and expand upon the engine as they would. We live by one principle: make the game you wish to see in the world. So we'd appreciate if you could make more of that game too.
(NB: If nothing else, making discourse maps with this editor turned out to be surprisingly efficient as a concept-mapping exercise. Rejected slogan: "Put the Aquinas in 'scholastic performance'.")