Controls: Click grid cells to toggle beats on/off. 4 tracks: Kick, Snare, Hi-Hat, Clap.
Play/Stop: Space bar or click Play button
BPM: Drag the BPM slider (60-180)
Volume: Adjust per-track volume sliders
Swing: Shifts off-beat notes for groove
Patterns: Save/load up to 3 patterns (keys 1-3 to load, Ctrl+1-3 to save)
Mouse: Drag across grid cells to paint beats quickly