darkhog: Unless there is a specific contractual issue regarding this between GOG and iD, it should be possible, because people behind ZDoom are pretty agreeable and probably would let you use it.

TheMonkofDestiny: I thought there was already a thread for this... oh well.

The distribution of a source port would be up to GOG and the creators/maintainers of the chosen port. Not every piece of free software can just get dumped into a commercial package without facing possible problems. A really good example is the re-release of the 2 SNES Bubsy titles - issues regarding distribution of the first emulator used forced a complete switch to something else.

There's also the underlying issue of GOG having to update installer packages every time a signifcant update to a port is made.

darkhog: Any particular reason it ships with (badly as I've found out with many of the DOS GOG titles - seriously, I can set up DB better in few moments than GOG staff can, just had to fix Daggerfall because it ran like crap because the conf file was all borked up) dosboxed version of Doom instead of some faithful source port like ZDoom for example (faithful as in uses software rendering instead of that opengl thing that just makes everything ugly)?

Unless there is a specific contractual issue regarding this between GOG and iD, it should be possible, because people behind ZDoom are pretty agreeable and probably would let you use it.