Unity is coming out with a new pricing model for 2024, where game developers will have to fork over money every time someone installs their game. this includes redownloads of already bought games, and downloads of games from places like game pass. it also applies to game demos and free games. it even applies if someone transfers a game from one device to another.
the policy applies if your company makes over $200,000 in yearly revenue and the game has been downloaded over a certain number of times in its entire lifetime.
there are rumors that gambling games and gotcha games are exempt.
https://blog.unity.com/news/plan-pricing-and-packaging-updates
I only knew a few of them! Unreal is obvious, Godot is another big one, and Unity is too.
I had a to google a bunch of them. The ones I knew--Source is half life. SCUMM is the game engine from LucasArts ... Monkey Island. (Similar to old school Sierra adventure games that ran on the AGI and then SCI engines.)
Groovie was the engine for The 7th Guest.