Glitches in The Adventure of Link
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Fairy Warp Glitch
This is a simple and surprisingly ill-documented glitch in Zelda II: The Adventure of Link, despite being extensively documented at one point. The glitch is extremely easy to replicate, and it requires very little on the part of the player - the Jump Spell, the Fairy Spell, enough Magic Power to cast both, and a location where Link can jump outside (or at least to the very edge) of the screen. Of particular note for the exploitation of this glitch are the second, third, and fifth palaces, but there are literally dozens of locations this can be attempted, with a differing degree of success.
Purpose of Glitch: Exploration of environment, unusual terrain and effect glitches, quick escape from Palaces, investigation of "Minus World"-like locations
Risk(s): Minor. You can become trapped, forcing a Save/Quit or reset.
Using the Glitch
Using the glitch is a very simple matter. Once you find a map (any map is possible, be it a dungeon room or a town) wherein Link can go partially or totally off-screen via the top of the screen (for this reason, the Jump Spell, while not necessary, is extremely nice to have), you can perform the glitch. To do so, select the Fairy spell, jump as far off the screen as possible, and Cast Fairy. Then, with Link off-screen and in Fairy form, attempt to move.
This will cause a "Falling" effect such as when Link falls in a hole. You will then wind up in a new area. In Palaces, this can be used with a second "warp" via falling (see the video) to arrive in completely new locations.
No Jump Spell
This is not really a glitch, but more of something that I don't think that the game designers intended. If you run at a ledge that you would normally need the jump spell to reach, jump, and reach the ledge in the height of your jump, you can make it. To make this work if you have to make two jumps, like in the cave south of Ruto, run up to the first ledge, jump (and make sure you land near the edge of the ledge) and jump again. If you do this right, you will make the jump, rendering the Jump spell unrequired to gain access to the lower area of the overworld.
This can only occur in the Death Mountain Trail or other caved bridges. The bago-bago will jump out at you. If at any point in its arial path hits a wall, it will slowly crawl through the wall. When it reaches the end of the wall, it will fall out at you like nothing happend.
- Zelda Chaos, ZeldaWiki's top glitch affilate that specializes in verifying hacks, explaining glitches, and providing up-to-date information on all things exploitable in the Zelda series.