This is a really slow and easy song to play, once you figure out how to play it. Aside
one part (which I haven't figured out yet) it basically follows the same few tones all
the song, usually in the same order.
[ Tab from: https://www.guitartabs.cc/tabs/s/sigur_ros/heysatan_tab.html ]
(I didn't tab it with the rhythm and timing, but that's very easy to figure out when you
to the song)
e------------------------|
B-0----------------------|
G-------------0----------|
D-----2---0-------4------|
A------------------------|
E------------------------|
It follows this a few times, then repeats the last two tones and Jónsi starts singing
it does.
That's the intro and most of the song for ya.