This is a resource of information on ''Ys: The Vanished Omens'', also known as ''Ys I'' or "Ys 1", on the Sega Master System.
While the information listed here is mainly useful for TASes, it can be helpful for speedruns too.
!!! Memory Addresses
!!! Overworld Movement
Pressing any D-Pad button for one frame will move Adol one pixel in that direction on the same frame it was pressed.
"Corner boosts" can be done, but they will only move Adol out of an object at his normal walking speed, so they aren't any faster or slower to perform.
!!! The Mirror Glitch
Pim's Pawn Shop Mirror Glitch is triggered when the player buys a mirror (there's only one for sale), attempts to buy it at least two more times, and then leaves the store.
Many different outcomes are possible when this glitch is performed. The game will usually freeze or crash, though it can also max out your level and HP, gift you random amounts of gold, soft or hard reset, jump to a random glitched or nonglitched room, or warp to the credits.
Here are some of the locations that can be warped to using the credits glitch setup alone:
!! Credits Warp
The main use of this glitch for a speed-oriented TAS is the credits warp, so this section will focus on that result.
For the glitch to warp to the credits, the overworld screen needs to be in a certain position. Specifically, it needs to be within a one-tile (8-pixel) range both horizontally and vertically. Not moving the screen down far enough usually causes a soft or hard reset, and not moving it left far enough warps Adol to a small blue room (possibly the room after fighting Vagullion).
In the image on the right, the areas of inverted color are the supposed "safe zone" for activating the credits.
Opening the menu once is also necessary before entering Pim's shop. The timing of this can affect the outcome of the glitch.
Different input while inside the shop can also affect the glitch's result. Button 2 normally advances through the menus and button 1 usually returns to the previous menu. However, there are times you can press 1 to dismiss a message that a casual player would normally press 2 to dismiss, and this can have a significant impact on the glitch result under certain circumstances.
As far as current knowledge goes, you must attempt to buy a mirror three times total to be able to warp to the credits.
!! Max Level
You can also use the mirror glitch to instantly attain max level from the start of the game. This is the glitch's most famous and longest-known effect.
The setup requires the screen to be as far north as possible. You can achieve this by walking down and left from the town entrance directly to the shop's door.
Enter the shop without opening the menu and attempt to buy a mirror three times, then leave as before. Your level will instantly become maxed at 10, and your HP (represented by a yellow bar) will visibly increase to its new max value of 255.
The area of inverted color in the image is the horizontal region with the best chance of maxing out the level without crashing while or after the HP bar is filling. A wider range of horizontal positions are possible, but not as likely to work.
The D-Pad and the 2 button (Menu) can sometimes be used to manipulate away crashes, though if pressed too soon after the glitch is performed, the game will crash even earlier.
Under certain conditions, this will also warp Adol to the entrance of the abandoned mine, fill his health bar but with some HP gone (red), or set the amount of gold to any value.
!! Other Notes
Buttons 1 and 2 are equally fast in starting a new game from the title screen.