Even Doom3 was released by Carmack... long after initial release, but yeah.
available source != open source license
Will less people buy your game because the source is available ? Absolutely not, we discussed this topic over the years plenty of times on this forum. There is also no need to encrypt or protect your code: nobody cares about code.
The only reason why you couldnt do this is license issues, as in you use proprietary code or algorithms that have NDAs or similar.
For example Cas built a Java steam API and he only gives out that to people who have signed the NDA
Yeah, that's sort of what I was thinking as well. I can't imagine many ways being open source could harm anything, beyond expert programmers picking apart my code and laughing at me.
You're right though that there is a difference between the concepts of open source and available source. I guess this is more of an "Available source" deal, because I wouldn't mind people distroing parts of the compiled source for modding purposes, I just don't want people sharing the .java files or trying to make their own entire games based on my code. I'd rather they have to buy the game to have access to them, and any distribution of the compiled files is for mod purposes only. Beyond that if they just want to poke around and see how I built the various systems like Pathfinding, lighting, etc, they can learn from my work and rebuild their own work based on it.