Ys: Ancient Ys Vanished/Versions

Original computer versions
Originally released for the NEC PC-88 on June 21, 1987, this version serves as the basis of comparison for every other version published. Throughout the rest of 1987, Ys was ported to a variety of other popular Japanese home computers, including the Sharp X1 (June 26), NEC PC-98 (August 28), Fujitsu FM-7/FM-77 (October 8), and finally the MSX2 (December 10). Other than changes to the graphics resolution and number of colors displayed, all of these versions are identical in content.

Famicom
Developed by Advance Communication Company and published by Victor Interactive Software on August 26, 1988. Out of every version created, this version is the most heavily altered from the original source.
 * The difficulty is high for a number of reasons, not the least of which is the enemies' high tendency to correct their position to better attack you.
 * Adol's movements are quite slow, as is his rate of hit point regeneration when standing still, which slows down the player's ability to progress. The highest level available to Adol is 24.
 * Several details were changed, including the arrangement of several maps and towns. In particular, the Plain now includes several statues that teleport you from one location to another, like the mirrors in Darm Tower.
 * Some boss battles have been significantly altered due to limits on the hardware's ability to produce a high number of moving sprites. As a result, the strategy of some boss battles are simplified, but the difficulty is increased.
 * New side-quests and items were added, such as the need to speak with a fairy to find an item that opens access to the Abandoned Mine entrance, as well as a second quest which takes place in Minea that unlocks the mine.
 * Darm Tower has been altered, and it removes the ability to walk around the exterior of the tower to get from one side to another. An additional mirror has been added, and the player is required to defeat the final boss once to gain a new item, and then use the mirror to access and fight the boss a second time before completing the game.
 * During the battle(s) with the final boss, pieces of the floor are not removed at the point of collision, as occurs in all other versions of the game.
 * Adol can read the Books of Ys without any assistance.

Sega Mark III / Sega Master System
Developed and published directly by Sega. Originally released in Japan on October 15, 1988 before getting translated into English and published in North America and Europe as Ys: The Vanished Omens. Only the Japanese version supports FM generated sound. Far more faithful to the source material than the Famicom version, but it still contains a few departures from the original version.
 * A number of the dungeons have a modified format. The maps are often presented as the mirror image of the original map, either up and down, left and right, or both.  This does not affect the content of the maps, only the layouts.
 * The game produces considerably fewer enemies for Adol to fight at any one time. This makes the effort to level up (or grinding) much slower.  In some cases, it is faster to leave an area and immediately return so that enemies instantly respawn, than to remain in an area and walk around until they come back on their own.

PC-Engine CD / TurboGrafx CD
Developed directly by Falcom, and published by Hudson in CD format on December 21, 1989, roughly one year after the CD platform was launched. Extremely faithful to the original. It includes an opening movie, new artwork, and a tweaked introduction which sees Adol exiting a ship and encountering Sara before he arrives in Minea. The only major change was the attempt to bridge Ys I and Ys II together as one game. As a result, Adol can achieve many more levels, but the higher levels are harder to reach. The amount of experience points that enemies provide scale down as Adol increases in level. The enemies and bosses at the end of Ys I have been tuned to be beaten by a mid-level Adol, while the enemies at the beginning of Ys II have been tuned to be more challenging since Adol no longer starts out at level 1. See Ys Book I & II for more information.

Sega Saturn
Developed directly by Falcom, and published by Nippon Victor on November 6, 1997. Released as part of the Falcom Classics compilation title. Extremely faithful to the original game but with higher resolution graphics. Though sharper, the palette is darker or more muted in comparison to the TurboGrafx CD version. Control over Adol has improved, allowing him to dash and move in diagonal directions. Beyond the graphics and some artwork, it is the last faithful conversion of the original game before the enhanced remakes were released.