Sound Test

An option in a video game where you can listen to all music from the game. May be available from the beginning, but often is an unlockable.

Sometimes it allows you to hear the entirety of a Wasted Song.

Originally it had a proper purpose. Arcade games would have a mode where a service technician could bring up a testing page to check for faults on a given board. This often included a sound test (both music and effects) as a way to check that the sound hardware was operating properly. (See also Debug Mode.) Why this was included in home console games (often with no arcade counterpart) was probably for the player's benefit.

It does seem to have gone out of fashion since the 16-bit days, possibly due to rise in popularity of the soundtrack CD market.

Action Adventure

 * One ROM combo in La-Mulana does this.
 * The Legend of Zelda the Minish Cap, after you get all figurines.
 * Iji has a classic sound test menu.
 * Castlevania: Dracula X Chronicles has CD's you can collect to not only listen to the music but also change the background music when you play through the levels.
 * All of the Metroidvania 's for the Nintendo DS have one.
 * Boktai gives you a sound test as a Bragging Rights Reward after collecting all the Silver Coins. One irritating feature was that some tracks could only be played when the game detected sunlight, and others could only be played when it didn't.
 * In One Piece, the Sound Test is the reward for finding all the small treasure chests and bringing them to Gaimon.

Action Game

 * The NES Ninja Gaiden games have a secret Sound Test that can be activated via a cheat. It includes both background music and SFX. Oddly, the the second game has a Cut Song that can't even be listened to here, only by hacking the ROM.

Driving Game

 * Diddy Kong Racing has one accessible via a cheat code, but it is sadly incomplete, displaying numbers rather than track titles, lacking the ability to listen to any of the dynamic tracks as anything but a mash-up of all versions at once, and even containing music not found elsewhere in the game.
 * Kirby Air Ride has a pretty good one, having all background music and noises. However, you must unlock the sound tests of many songs through gameplay.

Fighting Game

 * Home versions of Street Fighter games.
 * At least the SNES version of Teenage Mutant Ninja Turtles Tournament Fighters.
 * All three Super Smash Bros. titles. They even include every single sound effect in the game, along with all of each character's voice clips, attack grunts, Kiai, etc. You could spend literally days listening to everything, considering that the song list for Brawl alone tops out at around 300-some tracks. (Many would argue that it's well worth the time, though.)
 * Soul Calibur II had a voice test on each character info screen.
 * Dissidia Final Fantasy - again, you have to buy it.
 * Magical Girl Lyrical Nanoha A's Portable: The Battle of Aces has both a voice and music test in the Character Viewer.
 * Marvel vs. Capcom 3 has one that also includes a voice clip collection.

First Person Shooter

 * Registered copies of Wolfenstein 3D had "Robert's Jukebox", which gave the user access to three different menus of songs. However, you could find out about it only by buying and reading the Hint Manual.
 * Turok 2. Track 10 is unused, it is purported to have been intended for the Primagen battle, which reuses a previous boss theme instead.

General

 * Several old DOS games allowed in the Setup (and sometimes in the GUI) to do this.

Platform Game

 * Sonic the Hedgehog 1 (hidden), 2, and 3 (hidden).
 * Sonic 3D Flickies Island, Sonic R, and Sonic the Fighters.
 * The Sonic Rush Series, Sonic Advance Trilogy, Sonic Adventure and Sonic Adventure 2.
 * The Sonic Storybook Series, Sonic Heroes, Shadow the Hedgehog, Sonic the Hedgehog 2006 and Sonic Unleashed.
 * A budget re-release of Sonic 3 and Knuckles for the PC goes one better and includes .wav files of the music and SFX from all three original games and Sonic CD, apparently for no better reason than to give the fangame and Flash animation community a leg up.
 * That's background music for a screensaver app. Unfortunately, the music for Carnival Night, Icecap, Launch Base and Sonic 3's end credits are missing, presumably because they didn't want you to know that the PC version of Sonic 3 replaced those tracks!
 * Mega Man X has two in it's options. One for Music & another for SFX
 * Kirby games of all sorts have sound tests.
 * On the Game Boy Advance port of Donkey Kong Country, hold Select while pressing B, A, L, L, A, Down on the game select screen.
 * And in the SNES version, press Down, A, R, B, Y, Down, A, Y. Rare likes having Fun with Acronyms.
 * Donkey Kong Country 2 and Donkey Kong Country 3 also have music test cheats - but if you use all three save slots, the only way to access the Donkey Kong Country 2 music test is to delete a saved game, as it can be accessed only on the screen where you choose your game mode (press down five times with two-player mode highlighted). Very annoying. Donkey Kong Country 3 fixed this by using a password system for its cheats, including the music test.
 * Entering a specific cheat code in Banjo Tooie fixes the jukebox in Jolly's Tavern, granting the player access to the game's sound test.
 * Dynamite Headdy, and most Treasure games for that matter.
 * Star Fox Adventures has its Sound Test available from Slippy's part of the main menu... once you paid a certain Well for its Cheat Token and dropped it into the maze's well. The tracks have no names displayed, even numbers. And you'll probably want to turn the SFX volume all the way down, because every once in a while, Slippy snaps his fingers in time with... something, but not necessarily what's playing... which might not even be a tune!
 * Cosmos Cosmic Adventure had a sound test accessible from the main menu.
 * Purple has a sound test which unlocks tracks as they are first heard in the game.
 * The third world in the Wii A Boy and His Blob has a sound test as its big unlockable. It takes the form of a small level in the game, with the sounds accessed by feeding the friendly local blobs jellybeans. Like all the levels in the game, it also contains a few hidden goodies:.
 * Wario Land Shake It has one, although you'll need to complete all the missions for a level to unlock its music.
 * Wario Land 4 is probably an odd case, since it has a sound test made of completely new music not played anywhere else. And the karaoke theme from Palm Tree Paradise.

Puzzle Game

 * Meteos
 * The arcade game Tetris the Grand Master 3: Terror-Instinct has one, but it only plays one of the game's songs and three sound effects. This is enough to verify that the board is working but not enough to rip an OST.

Rhythm Game

 * Rhythm Heaven.
 * DJMAX games (save for Technika) have a mode called "Album" or "OST" that lets you listen to the soundtrack versions of the in-game songs. Even in DJMAX Online, which didn't have an OST mode proper, you could use background video mode to listen to the songs without having to play them.
 * Amplitude allows playing the studio version of any completed song.

Roguelike

 * Pokémon Mystery Dungeon - Explorers of Sky has the Sky Jukebox which is unlocked shortly after completing the first storyline. It has every piece of music from the game available to listen to (some might be locked until you've played through certain dungeon areas). You can even plug headphones in, shut the DS and listen to the soundtrack on the go. You'd think more DS games would have that last feature...

Role Playing Game

 * Mother 3
 * Earthbound, albeit only via its hidden Debug Mode.
 * Chrono Trigger (among the additions to the Play Station and Nintendo DS versions)
 * Golden Sun: The Lost Age has a pretty well-hidden one, which requires talking to a specific NPC in the multiplayer Battle Mode lobby while holding the L or R button. The sound test only lets you play songs that you'd already heard on that save file, but using a completed save file unlocks every track.
 * The Iris games from the Atelier Series let you unlock all the songs, that can then be played from the Extras option on the main menu. Mana Khemia, from the same game company, also had unlockable songs.
 * Breath of Fire III and IV let you build music shops in the optional Fairy Villages.
 * The World Ends With You has CDs as in game items, each of which has one song from the soundtrack.
 * Pretty much every game in the Tales (series).
 * In Final Fantasy X and Final Fantasy X 2, you had to actually buy the "spheres" that would let you listen to the music.
 * Most games by Tri Ace, including Valkyrie Profile and the Star Ocean games.
 * Most Wild Arms games.
 * Super Robot Wars games have varying degrees of this, from normal sound tests to karaoke modes and even the option to switch themes from different units!
 * Metal Walker has one in the area where you find the special Land Core.

Shoot Em Up

 * The Touhou games.
 * Thunder Force II through V. Strangely, there isn't one for VI, which doesn't even have an original soundtrack officially released.
 * Battle Garegga. If listening to the arcade version of Stage 7's music, "Marginal Consciousness", it keeps increasing in pitch indefinitely. Argh, my ears!
 * Zanac has an unused song which can either be heard in the sound test or pressing a certain button combination in Area 10.

Stealth Based Game

 * Metal Gear Ghost Babel had one as an unlockable for completing all the VR Missions.
 * Metal Gear 2 Solid Snake had an Easter Egg radio frequency which did this, and Metal Gear Solid Integral did a similar thing (but only with Wasted Song tracks).

Turn Based Strategy

 * Fire Emblem, from Thracia 776 onward.
 * Advance Wars: Days of Ruin (Dark Conflict for Europeans) had this, and were labeled with creative names like "Hope Never Dies: Brenners/O'Brian's (EU) Theme".
 * Disgaea. You have to buy the songs with in-game currency, though.
 * As an additional New Game+ bonus in the second Original Generation Super Robot Wars GBA game, entering a specific sequence of keypresses on the right menu takes you to the Sound Test page instead of the normal BGM Select.
 * Once you beat Luminous Arc, you can listen to all the music, sound effects, and dialogue.

Visual Novel

 * Radical Dreamers - at least the Fan Translation.