Some fun chords from Valve's game Portal 2. This song is during the Cave Johnson part of the single player campaign and is pretty recognizable. You have to listen to the recording if you want to find out how to arpeggiate the chords. If you use a square lead it can sound pretty cool. G B7 Em Cm A# F C# F# B7 G It just repeats from there. The beat is kind of weird but again just listen to the song for guidance.