Clozemaster is a language learning game focused on building vocabulary through mass exposure to sentences. The core mechanic involves filling in a missing word (a "cloze") in a sentence. It uses a spaced repetition system to re-test words and features a heavily gamified interface with points and leaderboards. Sourced from a large corpus of translated sentences, it's an excellent tool for intermediate learners to move beyond basic vocabulary and see words used in a wide variety of contexts, which can implicitly reinforce grammar.