The reconstructed source builds with what i'm pretty sure is the original Microsoft C compiler and toolchain. It produces a byte-for-byte match with the original executable, aside from a four-byte correction for what appears to be a patch applied after linking. So it should be pretty close to how the original game was made; although it can't be said that this is the "original source code".

I've also used that source to create a modern build of the game, in the `reciv` repository.

Like most people, I'm in two minds about the benefits and downsides of LLMs. This work also builds on OpenCiv1, which probably deserves most of the credit - not only did I direct the LLM to use that work; but it was almost certainly in the training data.

Qualms aside - I couldn't resist having a look inside one of my all-time favourite games. There's a few attempts at Civ 1 including recent LLM ones. But i'm not aware of any that publicise the resulting source code.