German uses Konjunktiv II for unreal or hypothetical situations (Wenn ich Zeit hätte, wäre ich glücklich.), wishes, advice and polite requests. The key forms are wäre (sein), hätte (haben) and würde + infinitive for most other verbs; the modal verbs and some strong verbs have their own one-word forms (könnte, müsste, käme, ginge). For the past you use hätte or wäre + Partizip II. In each question you see a German sentence with a gap and its English translation, and you choose the right form from four options. After every answer you see the form and a short note explaining it.
Choose B1 (wäre, hätte, würde), B2 (modal and one-word forms), C1 (past Konjunktiv II) or Mixed. A round has up to 10 questions, and you have 3 lives. The game is free, needs no account and keeps your progress in your browser.