Arguably the single best entry in the Metroid series, this SNES title also has some of the best music on the console. Exploring the underworld of the alien planet Zebes is not for the faint of heart. It's a foreboding place filled with underwater caves, subterranean jungles, hellish magma chambers and a haunted derelict spacecraft all infested with horrific creatures. Thankfully the heroin, Samus, is a fearless professional willing to risk the hazards as the opening theme illustrates rather nicely.
I actually prefer the 64-bit version of Star Fox a bit more than the SNES version if for no other reason than all the hammy one-liners. That said, the original Star Fox has some of the best 16-bit starting level music out there. It does a good job getting the player into the high intensity gameplay as well as selling you on the idea that the FX chip can produce fun games to play even if the graphics are kind of crude.
I've mentioned the music score for Target Earth once before, but I'll mention it here again because, yes, it's that good. While the title theme is the example I chose to highlight here (as before), the truth is pretty much the entire OST is great. By all means check out the other tracks, particularly the ending song.
I'm cheating a bit with this one. Rune is actually only 14 years old at the time of this posting which makes it nearly a decade newer than some of the oldest music pieces on this list. The reason I added it anyway is twofold. First, I wanted to include something that was on the PC. Second, as far as Norse themed tunes about Icelandic sagas and epic journeys go this belongs on the must-listen-to list.
Streets of Rage (or Bare Knuckle as it is sometimes called) belongs on everyone's top five list of best "Beat'em Ups". It also has some of the finest music you can find on the Sega Genesis. The number of memorable tracks are too great to choose just one, so I defaulted to the first stage theme...which actually does a good job of expressing the franchise rather well, I think.
If you thought Rune was too new to be here, your going to really be annoyed with this final choice. Hotline Miami is hardly "old school" having came out in 2012. However, it is set in the same approximate time frame as when the other games on this list were released. Better still, the soundtrack takes a lot of inspiration from that time period. So while not chronologically appropriate it is stylistically a good fit. Enjoy!