Third-party

Component	License	Source / note
SDL2	zlib	system / Homebrew / ports
Placeholder graphics	generated in-engine	solid colors / rects — no external sprites yet
Optional future packs	CC0 / CC-BY	e.g. Kenney.nl, OpenGameArt (attribute when added)

Forbidden

KKnD / Westwood / EA game data, ISOs, ripped sprites, music, maps, or reverse-engineered proprietary assets.