NN555Sync

NN555Sync is an offline rhythm drill game built around visible timing, simple patterns, and precise taps.

Choose from 40 handcrafted levels across four chapters. Early levels focus on steady single taps, later levels add adjacent alternation, simultaneous double hits, and hold actions. Each level is designed for a 45 to 120 second practice session and keeps the timing information fully visible even without sound.

Before playing, you can complete a one-time local calibration step by following a flashing target for eight taps. The app stores the suggested offset on the device and also lets you restore the default timing at any time.

During play, the board shows three lanes, a judgment line, progress, combo count, and instant feedback for perfect, good, early, late, and miss results. Hold notes show start and release states. After a pause or app interruption, the session resumes with a three-beat countdown so the next entry feels stable and predictable.

After each session, you can review accuracy, score, max combo, lane breakdowns, timing distribution, and the weakest 15-second segment. That segment can be replayed directly for targeted practice.

The app also includes local preference controls for sound cues, haptics, lane mirroring, reduced motion, assist patterns, judgment line size, and manual timing offset. Progress, best accuracy, recent results, and calibration status are stored locally on the device.