Pick a key, a feel, and a tempo — the app loops a full 12-bar blues band (drums, walking bass, and 7th-chord comping) for you to solo over. The pentatonic box below shows where to play, and lights up the current chord's target tones as the changes go by.
Hit Play and the band loops a standard quick-change 12-bar blues in your key. Solo using the minor pentatonic box shown on the fretboard — amber dots are the root, the teal dot is the bluesy b5. As the chords change, the notes ringed in gold are the chord tones of the chord playing right now: land on those to sound "inside," and pass through the others for tension.
Try Shuffle for a classic swung blues, Straight for a rock/straight-eighths feel, and Slow for a 12/8 slow-blues ballad groove (the tempo auto-adjusts, but tweak it to taste). Mute the Bass to practice locking with the drums, or mute Chords to hear your line against just the rhythm section.