Can't tell a darn thing from the linked page or the home page. What language? What platforms? Either I'm really dumb or the page is incomprehensibly designed with no actionable information.
WalterGR 1 hours ago [-]
The "What is it?" section of the introduction in the manual is informative and answers your "platforms?" question. Reading between the lines it seems like Lua is the only supported language.
https://github.com/raysan5/custom_game_engines
https://docs.crownengine.org/html/latest/introduction.html
The Github page suggests the engine itself is mostly written in C++ and Vala.
https://github.com/crownengine/crown/