This release introduces ray-casting in your games, access to a surface's depth and stencil buffers, the ability to place text in your rooms inside the editor (and manipulate it later on in-game, if you wish), a lot of new additions to the in-game debug GUI functionality, and more...
As well as all the new stuff above, this release has a large number of important stability, performance, UI/UX, and QoL fixes that should hopefully make things a lot smoother as you're using GameMaker.
Note also that there are quite a few important fixes for building projects, collisions, audio/Sequences functionality, and other things which may require you to have to now make some changes in your projects, so please do read the full notes carefully.
And for a little more on some of the headline features you can also see [url=https://gamemaker.io/en/blog/release-2024-6]the release blog post[/url].
[url=https://releases.gamemaker.io/release-notes/2024/6]Full release notes[/url]
[url=https://github.com/YoYoGames/GameMaker-Bugs/milestone/11?closed=1]Milestone page ("changelist")[/url]