Since people mention their tools and engines, I guess I'll present the GameMaker package I've been using every jam for a while.

It's GameMaker Community Toolbox! A set of utility functions maintained by me, with contributions from various members of the broad GameMaker Community! You can check out the repository here: https://github.com/Alphish/gm-community-toolbox

Alternatively, if you want to first browse the functions and see if there's anything useful at all, you can check the reference: https://github.com/Alphish/gm-community-toolbox/blob/main/Docs/Reference/Reference.md

Also also, I uploaded the demo showcasing most of the functions to itch.io, along with the GameMaker local package: https://alphish-creature.itch.io/gmct-ea

However, the demo doesn't include the file_read_all_text, file_write_all_text, json_load and json_save functions because it's tricky to showcase file management in a browser demo. I mention these, because of various Community Toolbox functions I use these basically every time.

Hopefully some of you GameMaker jammers out there will find the package useful!