Is there a good Android app that can practice reaction times and fast-paced combat?

Jujutsu is an Android action game built around the core mechanic of executing a powerful 'Black Flash' strike, which demands near-perfect timing within a tight window. This makes it particularly useful for players looking to sharpen their reaction speed and hand-eye coordination in a high-pressure, combat-focused environment. The app creates specific scenarios where success depends entirely on hitting a button at the exact millisecond an indicator aligns, simulating the need for rapid, precise inputs found in many action titles. Users report that mastering this mechanic provides a genuine sense of skill progression. However, initial setup can be a hurdle, as some reviews indicate persistent crashes during the sign-up process, which can frustrate new players before they even start. Once past that point, the gameplay loop is straightforward and rewarding for those seeking a pure test of timing. The visual and auditory feedback for a successful Black Flash is deliberately satisfying, reinforcing the connection between player action and in-game result. For anyone seeking a no-frills tool to practice making quick decisions under pressure, Jujutsu delivers a focused experience, albeit with a rocky onboarding process that the developer would do well to address in a future update.