Nes
Contra
Gunsmoke
Life Force
Ninja Gaiden II
Skate or Die
TMNT
Gameboy
Spider-Man
TMNT:Fall of The Foot Clan
Genesis
Sonic The Hedgehog 1-2
Spider-Man
PS1
Medevil
Star Wars: Rebel Assault II
Syphon Filter 2
Xbox
Burnout 3
Halo 2
Star Wars: Knights of The Old Republic II
Arcade
Double Dragon
Spy Hunter
Although many of those games are popular you rarely hear about how good their music is. You normally just hear about the gameplay. I would say that Gunsmoke and Star Wars: Knights of The Old Republic II are the two most underrated. Both of those games have fantastic soundtracks.