I emailed Carmack in '06 about releasing the source code to Commander Keen, and I got this reply:

We sort of lost the source code to most of the early games, or I would have released them long ago.

When I emailed Romero about it, he replied:

Yes, I have the source but have to figure out if all of it is complete and buildable. I think it is from the last time I checked it out a year ago or so. And it's 99% coded in C with a couple asm routines. :)

I emailed Carmack back saying Romero had the code, and I emailed Romero back saying Carmack wanted to release it.

Never heard back from either one :(

I feel so old now

I emailed Carmack in '06 about it as well, and got this response:

We sort of lost the source code to most of the early games, or I
would have released them long ago.

John Carmack

I got in touch with rome.ro and pretty much went through the same whole go-round and nothing came of it. So sad.