AdaDoom3 is an effort to rewrite Doom 3's code-base in Ada. The id-Tech-4-BFG open-source code-base is being used as the starting point. Planned goals are Doom 3 BFG level loading support, native ports for SDL, Xbox 360 controller support, multi-monitor windowing, working multi-player, and more.
With this Ada port the developers hope to even implement threaded rendering and make use of the Vulkan graphics API.
Those curious about this experimental effort to rewrite Doom 3 in Ada can find it hosted at AdaDoom3 on GitHub.