I'm listening to a playlist consisting of 10 different versions of Akuma's theme.

[kane_magus]

That's 10 official versions of his original theme from Super Street Fighter 2. Not fan-made remixes (though, technically, I guess the HD Remix version would count as "official" even if it was fan-made). Not the totally different themes that were used in Street Fighter 3 or Street Fighter Alpha 3 and the like. Ten official remixes of the original theme.

Aw what the heck, let's just consider this to be Game Music Thing 8.

Super Street Fighter II Turbo (CPS1)

Watch on YouTube

Super Street Fighter II Turbo

Watch on YouTube

Super Street Fighter II Turbo (Arranged Anniversary Edition)

Watch on YouTube

Street Fighter Alpha (CPS1)

Watch on YouTube

Street Fighter Alpha (CPS2)

Watch on YouTube

Street Fighter Alpha 2

Watch on YouTube

X-Men vs Street Fighter

Watch on YouTube

Capcom vs SNK 2

Watch on YouTube

Super Street Fighter IV

Watch on YouTube

See also Gouken's theme.

Marvel vs Capcom 3

Watch on YouTube

(EDIT)

Oni's Theme from Super Street Fighter 4 Arcade Edition

Watch on YouTube

Akuma's Theme from Asura's Wrath

Watch on YouTube

Oni's Theme from Asura's Wrath

Watch on YouTube

(/EDIT)

Okay, that ended up being more effort than I was expecting to put into this when I started this post (which was just going to be an off-hand mention kind of a thing originally), but oh well. ¬_¬