Ys (イース, Īsu?, IPA: [iːsu̥]) (English IPA: /ˈiːs/) is a Japanese computer and console role-playing game series, and Nihon Falcom corporation's flagship franchise. It started on the NEC PC-8801 in 1987. Ys titles have appeared on the MSX2, FM-7, Sega Master System, Sega Mega Drive, Famicom, Super Famicom, Nintendo DS, PC, PlayStation 2, PlayStation Portable, TurbGrafx/PC-Engine CD-ROM, cellular phone, and on the Wii's Virtual Console service from Nintendo. The common misspelling "Y's" arises from a typographical error in the packaging of the English-language versions on the Sega Master System.

The Ys series chronicles the adventures of Adol Christin, a red-haired young man with a zest for adventure and an uncanny knack for being in the right place at the right time. Gameplay always revolves around Adol, though his comrade, Dogi, is a frequent companion in his travels around Esteria. Adol is the only truly playable character in the series. Feena was a non-controllable companion in Ys Eternal, and Tarf was set up in Ys II Eternal. Several characters follow Adol in Ys IV.

The most used gameplay mechanisms involve using the directional pad to fight, where the player must literally run Adol into the enemy. Tactics developed from this involving running into the side, back or slightly off center of the front of most enemies. Ys III: Wanderers from Ys played a bit more like a standard side-scrolling action-adventure type of game, using an attack button and D-Pad usage giving Adol a regular slash, a crouching jab, a standing upward thrust or a downward thrust while sailing through the air. The classic control scheme made a comeback in Ys IV: Mask of the Sun. With Ys V: Kefin, the Lost City of Sand, the game became much more of a top-down affair similar to The Legend of Zelda series. Ys VI: The Ark of Napishtim graphically departed from its predecessors, using three-dimensional graphics and hack-and-slash gameplay. The Turbo-Grafx games (particularly Books I and II) are considered the best of the series by the older fans of the original series.

Source: Wikipedia