[cellularmitosis]

If you count raylib as a GUI, yes!

https://github.com/tantona/janetroids/blob/master/main.janet

[eggy]

And that is 379 LOC for an Asteroids clone which includes some inline defined math functions instead of an include to an external math lib. Raylib is great for the GuI stuff (it is an immediate mode GUI, because games), and it is written in C.

[ptato]

good enough