I actually think this is a cross-over philosophical question.
There are songs that obviously execute at an extremely high level in complexity and melody. In that department, I
love Double Dragon II's intro track (especially by 1:20 or so). Everything about it is just so good.
But then there are games that we've played obsessively, day after day. And some of those games (
Curse of the Azure Bonds for me) - become total earworms that give you a very warm feeling when you hear them. The music from some of your favorite games might sound simplistic to the uninitiated, but to the game-obsessed, the music from those games could evoke intensely strong, positive feelings.
So, Doube Dragon is a game I might play with my son and never again, but I recognize the mastery of the intro track. Yet a more simplistic sounding tune may trigger deeper personal connections for me.
Every now and then, you hit a game that does both. It is both one you obsessed over
and had a brilliant intro or soundtrack.
Defender of the Crown, I think, hits close to that mark. Although that could be nostalgia talking. But it's pretty cool.
Desert Strike, with its digitized voices (
hear it on YouTube), is also pretty freaking amazing and intense. I think
Monkey Island needs to be in the conversation, too, just because its 1) such a great tune and 2) the instruments are amazing. And Turrican II.
Dang, man, this is really hard to answer!