Gdevelop 😀

Tic-80
Game Maker Studio
Unity :'D
and Godot sometimes

Team Construct here, I love its workflow, perfect for quick jams

Pygame

This is my first jam, and I used Unity to practice and learn new things about it

I’m using Love2d (Lua)

godot 3.5

unreal engine 5. Because why not go way overkill for a tiny pixel art game. 

don't judge but.. um... Scratch T_T

Godot 3.5! All the source code is on GitHub, but after seeing the release notes for Godot 4 Beta 6, I think I'm gonna finally migrate to Godot 4 now. I wouldn't be able to game jam as efficiently as I have been if I were still using Unity, so if anyone reading this thread isn't sure what engine they should try out next, I strongly recommend Godot!

I used Godot, it's become my main engine in the past few years. I've noticed the node system helped me a lot with the quick prototyping needed for a game jam.