With hundreds of options to choose from, FourChords Guitar Karaoke lets you add a customizable accompaniment to the lyrics that helps you keep up as you play. The music is not included, but you can see the notes that you have to play at each moment. If you don't remember the fingering, you can look up a YouTube video to learn how to play the song.
The best part of this app is that you only need to learn four chords to play an entire song, so with a little practice, you can play hundreds of songs. Since the FourChords Guitar Karaoke catalog is so extensive, you can also mark your favorites to access them more quickly later.
The genres are also pretty varied so that no matter your musical taste, you'll find something you like, including pop, rock, children's music, classical, Christian rock, etc. Just look for your favorite songs in each category and surprise your friends.