- I use Ren'Py, it's a python based visual novel engine. Easy to understand, ports to a good number of platforms and is free for commercial use.
- I just came across Bfxr, a cool sound effect making tool.
- I also love Hexels as a graphic program, it's a pixel art program that lets you draw in different shaped hexels.
- Medibang and FireAlpaca are both great paint tools for those who want to draw, they're free, available on plenty of platforms and offer cloud saving.
- Someone needed to mention presskit()