Hi! Some little unsolicited code review from me)

1. Current ebiten also needs Layout meth to be implemented and some func deprecated. Maybe you should add specific version, that you used for this game :shrug:
2. Change direction before g.updateCounter check will make snake control more smooth
3. Duplicate code at g.score++ section. Looks like it there was food that can increase snake length for > 1 tiles, but code wasnt removed
4. g.speed was setted to 10 inside and outside restart func. Maybe it should be setted only inside restart func?

Anyway, nice game example! I like it! Thx :D