Guitarist

Guitarist is a complete electric guitar solution for Mac. The app provides guitar riffs, combined with amps, wah pedals and effects.The actual guitar player has been transformed into a step sequencer system that allows control about playing styles, chord progressions and song structures.

Guitarist can be played live as well, with just two fingers you can combine chords and patterns easily.
You can choose from factory chords or just create your own chords on the fingerboard. The Action section allows you to tweak the sequence in realtime and apply timestretch, looper or other crazy effects.