Modernizing Source Engine, while making it available.

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█ defun █░░ a LISP programming language word for functions.
█▄▄▄▄▄▄▄█░░ The name is inspired by Portal 2's music "(defun botsbuildbots () (botsbuildbots)".
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Hello. I suppose you're not happy with me using leaked Source Engine. If that's the case, then i'm sorry, but it had to be done. Before DMCAing this project, i'd like to see you open-source the entirety of Source Engine: just replace proprietary software/libraries with open-source or just remove 'em so that community can reimplement them back, then ask id Software for GPLv2 license. After all, you're now working on Source 2, so why not make the modders happy? It's been 12 years since Source SDK 2013 🥺

Nope, the project's still not dead.

This was written from my memory and it is likely that something might not be correct.

You see, Source Engine was previously GoldSRC, which was previously a work-in-progress version of Quake 2 Engine.

Valve purchased the license for WIP Quake 2 Engine, which did not allow them to open-source the codebase.

When developing Source Engine, Valve Software heavily modified the codebase, making the game a separate folder.

After Half-Life 2, Valve Software released Source SDK 2004, open-sourcing the code that wasn't from the licensed Quake 2 Engine.

But before Half-Life 2, id Software open-sourced Quake/Quake 2 engines with GPLv2 license, and its proprietary licensees had to contact them to get that GPLv2 license for their codebase.

It is 19th of July, 2025 and Valve Software still did not do anything to make their sources be available for open-sourcing. And it does not look like we're going somewhere. All SDKs and no engines makes Jack a dull boy.