Clu Clu Land
One of Nintendo's lesser-known early titles interestingly had this "sequel" released near the end of the life of the Famicom Disk System. As a Disk Writer-only release, it's one of the rarest and most sought after FDS games, easily fetching between $400 and $800. In total, there are three versions of Clu Clu Land: the original NES cart release, the Vs. Arcade release, and the FDS version. The FDS version is strongly based on the Vs. Arcade release, though with some differences. It was also included as a game you could unlock in Animal Crossing for the Gamecube, in which it's referred to as Clu Clu Land D, with the “D” likely meaning “Disk”. In Clu Clu Land, you control a character known as Gloopy (Bubbles in the American version). The goal is to help her navigate levels and collect all of the “Ingots” (gems) that are placed randomly around the level. You cannot directly control Gloopy, except by extending her arms to grab onto oncoming poles and spinning her around to change direction. You must also avoid enemies, known as Unira, that will come out of black holes. Both of these obstacles will kill her on contact, but you can safely cross black holes as long as you are holding onto a pole. Unira can be halted with Gloopy's stun ray, which causes them to freeze and turn into small orange balls. Pushing these balls into the wall will give you points and remove the Unira temporarily from the screen. The controls take some getting used to, and are likely a reason this game is not fondly remembered, as it’s not easy to just pick up and play. So what are the major differences from the original NES release? For starters, there are twice as many level designs. A new enemy known as “Boss Unira” also appears after defeating enough Uniras on a level. It's a large version of the regular enemies that will rush after you, but can be defeated in the same fashion as its normal-sized brethren. Another addition is the inclusion of a high score table to save your score. The music is also different, and changes between levels as well. An expert mode is now available, too, which instantly activates a rule that normally doesn't occur to level 23, which causes ingots to flip around to a dark side if they are crossed more than once. When they’re dark, they don't count as revealed, so you have to take great care in this mode. The FDS and Vs. System releases differ in the fact that the Vs. System features no expert mode, and the purple levels are black instead. Due to the extra levels and expanded features, the FDS port is the best version of Clu Clu Land. Beyond being hidden in Animal Crossing, it was also released on the Wii Virtual Console.