The Famicom Disk System was an add-on for the Famicom (the Japanese NES) that loaded games from floppy disks - which were cheaper, but less reliable than cartridges.
The Disk System List
Ai Senshi Nicol
Love Warrior Nicol
A Zelda-esque game by Konami that only came out in Japan on the Famicom Disk System. Another damn fine example of an excellent Konami game lost in the past. This one's entirely in English, including the cut-scenes and dialogue, so there's absolutely no barrier for the English crowd. Excellent graphics for 1987.
Almana no Kiseki
The Miracle of Almana
A game by Konami starring "NOT" Indiana Jones that has some of the best gameplay on the Famicom. Very Castlevania-ish, and even has some multi-directional whipslinging and hanging later seen in SC4. It's a real shame this wasn't ported over here (probably because of Jones copyright issues) because it's such a damn fine game. Available only on the Famicom Disk System, unfortunately, but there is little to no Japanese knowledge required really so give this gem a try!
Nazo no Murasamejō is the black sheep little brother of Zelda and Startropics. The second game released for the Disk System, you play as Takamaru, a samurai who must save his ancient Japanese land from an alien demon that has corrupted all the local daimyo. He must traverse the land to the castle Muramase and annihilate the evil force once and for all. It plays like Zelda, but is totally linear and fast paced, entirely based on action instead of exploring. You have a limited number of powerups, and enemies come from all sides, making the game's difficulty soar the fucking roof. A real gem though, shame we didn't see anymore, it had great series potential. A homage mode to this can be found in Samurai Warriors 3 on Wii, which is localized, so we finally get to see Takamaru overseas. This game is also on the 3DS's Virtual Console outside of Japan for the first time ever.
Otocky can be described as a musical side-scrolling shoot 'em up. The player's spaceship has a ball for a weapon, which can be fired in eight directions; each direction corresponds to a different musical note. The note plays when the player presses the fire button, and is also quantized in time so that it matches the beat playing in the background. By using the weapon selectively the player can improvise music while playing. The ball is used to destroy enemies by touching them, and also to catch various types of objects: Musical Notes which must be collected to finish the level, letter 'A's which change the musical instrument sound produced by the ball, and letter 'B's which provide a secondary weapon. The ball gets smaller when the player is touched by an enemy, until the player loses a life. Finishing the game unlocks a music editor which makes it possible for the player to freely compose their own melodies.
Super Mario Bros. 2
Super Mario Bros: The Lost Levels
The real Super Mario Bros. 2, but was later released as Super Mario Bros: The Lost Levels in different compilations. this game is balls hard compared to the other three SMB games on the system. This time around, Mario and Luigi actually have different control styles. Play as Mario for that classic feel, or play as Luigi if you enjoy gratuitous amounts of momentum and high jumpan. This game is kinda lazy in that it looks way too much like the original, but it's great if you like a challenge and have already mastered SMB1. The later levels in this must have been designed by a fucking troll though. Also, POISON MUSHROOMS.