Completely subjective list of places with good quality assets (graphics, sounds) in formats useful with Castle Game Engine. See and post on the
#assets channel of our Discord for more.
Game art (3D, 2D, sounds) uploaded by various artsts on clear open-source licenses.
Hint: Do you want to share an asset you made and tested specifically for CGE game? Upload it to OpenGameArt.org with
[CGE] in the name.
Sprites, 3D models, sound effects on a public domain ("do what you want") license.
3D models, in glTF format, uploaded by various arists. Some free (on clear licenses, like Creative Commons), some paid.
3D models in Blender (which you can export to glTF easily). Uploaded by various artists. All on Creative Commons licenses.
Many 3D model packs, on a public domain license.