Nobody does 'fun' music making apps quite like Smule, and its latest, Magic Guitar, has the added advantage of being free.
This appears to follow the blueprint laid down by the company's other Magic apps (Piano and Fiddle): you hold your iPhone/iPod touch like a guitar neck and play the beams of light that appear at the appropriate times.
You can shake to add vibrato or drag fingers to bend pitch, and there are different guitar sounds to choose from, too. The Magic Guitar Songbook contains tracks from The Rolling Stones, Kiss, Nirvana, Coldplay, Bruno Mars and many more. Check out the video below to see someone channelling their inner Jimi Hendrix with a version of The Star Spangled Banner...
Download Magic Guitar now from the App Store (opens in new tab).