4 ms·
If flashcards count as games, then Memrise (or Anki which is FOSS but you have to setup the gamification aspects yourself) If ELO rating grinding counts, then
by gfd 4y ago
If flashcards count as games, then Memrise (or Anki which is FOSS but you have to setup the gamification aspects yourself)
If ELO rating grinding counts, then chess or competitive programming. Or any game with a competitive scene.