Games From Scratch is a prolific Youtube channel dedicated to helping solo and small team gamedevs with tutorials and tools. They really do post frequently, so if I linked to everything they made it’d overwhelm the blog, but it’s been a while since I referred to them, and they just made a nice omnibus video of free tools. There is a sponsored section in it, but if that kind of thing bothers you I suggest using the browser extension SponsorBlock, which shows time-wasting sections on the Youtube timeline in different colors.
Here is the video (13 minutes):
Here are the tools recommended, along with links (which the video maker neglected to provide):
Blender (3D modelling)
Godot (game engine)
O3DE (game engine)
Krita (raster art)
GNU Image Manipulation Program (raster art)
Audacity (audio editing)
Tiled (map creation)
Inkscape (vector art)
Pixelorama (pixel art & animation, can be run in browser)
DPaint.JS (pixel art, in-browser, recreation of Deluxe Paint for Amiga)
GraphicsGale (pixel art)
Material Maker (procedural texture creation)
Ucupaint (texture painting extension to Blender)
MagicaVoxel (voxel-based painting, Windows & Mac only)
SculptGL (browser-based sculpting)
LDtk (2D level editor)