I mean, Unreal Engine and CRYEngine are source-available if not open-source. I'm not sure that it's so far-fetched to call for the open-sourcing of game technology like engines.
But unlike Unreal, the source code license is reference-only (yeah it sounds ridiculous, but you are not allowed to modify and recompile the source code.) Someone sent a pull request to the code (a bugfix which solved a lot of GC performance issues), only to get rejected because of the license (although it later got patched internally in Unity)
But how does that affect the above comment trying to spin this as an archival thing? If you want to port to a new platform one day when Unity is bottom up the fact they’re not accepting patches isn’t going to matter
The archival angle works for Unity because the actual game code is run in a .NET CLR (Mono in most variants of the engine).
Maybe the best way forward is source code escrow the way Trolltech arranged with Qt. They had a deal where the if they ever stopped working on an open source Qt, the last release would become automatically BSD- or MIT-licensed and thus available to all. They had the details worked out nicely. I really believe that Unity should be pressured into such a deal. It is not important now, but it will be an entirely different thing 5 to 10 years after they fold (if ever).
These games are closed source with IPs owned by multi-billion dollar corporations.
The engine being closed or open is of literally 0 consequence. Any 3rd party reverse engineering these games to run on a new platform would already be breaking licenses and trademark laws.
How much of the Steam cataöog is owned by big publishers? 10%? These generate most of the revenue. Bit there is this incredibly long tail of smaller games ownes by small publishers and indies who self-publish. These are virtually exclusively Unity engine titles. And there is no way any of thesw could afford the 6 or 7 digits for a source license. And unless thungs changed, you won't even considered eligible without an exceptional track record.
Which just goes back to my original point, if these small titles had been interested making open source games they wouldn’t use Unity.
It doesn’t matter how big the owner is anyways, you don’t own the IP.
So Unity being open sourced wouldn’t matter for a 3rd party trying to port it, and the majority of these small titles that initially willingly built on a closed sourced platform are not going clamoring to port their own games to new platforms decades from now.
Do you have any experience in game development? Unity is an affordable engine that saves small developers a tremendous amount of time by being a well rounded powerful and easy to use package. It has absolutely no open source alternative and not using either it or Unreal is economic suicide.
Most of the Unity titles might be forgotten in a decade. But some (which peobably means a few hundred) will not. Their devs might have trapped themselves by being locked in by the engine.