With OpenJK being a thing can GOG include Mac and Linux binaries for the release and update to show support for both Linux and Mac? GOG doesn't even need permission because it's released under the GPL.

What is the status of OpenJK then? Crash much? Single player completable? Would have to be pretty solid for GOG to include it: if they package it, people expect them to support it. Besides, distributing anything under GPL is a hassle because they'd have to include the source code.

I've now completed single player with OpenJK. It crashed (segv) after what I assume to be the final cutscene. There was also a nasty bug causing animation not to start in some cutscenes. Fortunately I found a workaround: quit the game, from the console if nothing else works, then restart from checkpoint. There was always a checkpoint at the failing cutscenes, which on restart ran just fine. Basic gameplay seems quite stable. So yeah, technically single player completable but needs some fixing.

While it is great to highlight that this exists, it is unreasonable to expect to support community efforts to port to other platforms. It could be significant work for something that doesn't have commercial quality/testing behind it.

Also while no individual will run into issues building or using community projects like this, a distribution company like GOG could have issues offering solutions for platforms they are not explicitly licensed to offer.