Since 1987, the war has started Ys series has grown into a huge series in its own right, and has continued to go from strength to strength in recent years. With more than ten online entries, lots of upgrades and a few decent spins, there's plenty to occupy your time.
6:38

related
All Ys games listed in chronological order
The Ys series remains a famous, but well-kept secret in the world of JRPG games. Here's how all the games fit into the series schedule.
But as with the long-standing series, the first question in your mind is whether the Ys game is one big story, or something else in the mythology similar to Final Fantasy. It's a tricky question that made the focus of the story even more difficult as the game progressed.
Is Adol the main character in every Ys game?
The first step to understanding the game Ys, is to understand Adol Christin, the red-haired actor. In every Ys game that exists, Adol doesn't just appear, he is the main character in the adventure. In fact, Adol is the only playable character in the game.
The protagonist since the first game of the series, Adol is usually not made to be a person of great importance, but a noble adventurer who wants to see the world and help those he meets. And that's exactly what happens. Most of the games are introduced to you as just another legend in Adol's grand adventure, with no strings attached.
However, this is not always true. In Ys Origin, released in 2006, we see the world long before Adol Christin. This game was the first to give more importance to the larger setting of the Ys game since its introduction. Since then, both mainline and spin-off, Adol has appeared as a main character. Not always in chronological order.
Adol does appear as a playable character in Ys Origin, although this is an add-on feature and not canonically recorded.
How many Ys games are there?
Currently, counting only exclusive games, including remakes and not remasters, there are about 17 games. This is not an exact number, as many of the updates are also built in. For example, 2005's The Oath In Felghana was a remake/reimagination of Ys III, but was later remade for the PSP in 2010, albeit with a few minor changes.
In this we count the original games, and then the latest updates of them. That's about 17 games. Also somewhat confusing is the fact that there are two Ys IV games, Mask of the Sun, and The Dawn of Ys, both of which were released at the same time. The stories of these two games were combined in Ys: Memories of Celceta, another improved version.
As you can probably tell from all of this, sticking to a strict schedule is a bit difficult because it can change as soon as a game is finished, the story changes with it.
Are every Ys game part of the same story?
eSo that brings us to the big question: are all the Ys games a single continuity? Yes! In the sense that all games take place in one timeline and everything lives together, the game is one big and unified story. However, the game doesn't really follow a single plot. In this respect, they are more like television series.
You can pick up the Ys games in any order you want, and they'll give you enough of a synopsis at the beginning to let you fully appreciate the story and character of the current game. But there are exceptions. Ys I and II are direct sequels. The original Ys III, which got the Oath in Felghana remake, also lets you know that it's a sequel to the original two games, albeit more closely related.
Ys IV, however, is said to be set before Ys III, and from this point the chronology of the series is no longer linear, and with that it is necessary to follow the story in special order.
Sorry for some references to other games and rare appearances of previous characters, the game stands on its own for the most part. This means it's easy to jump into the games you want, even if there's a technical schedule to worry about.
Although it's called Ys Origin, it's more literally about the origin of the world, and draws heavily from the stories of Ys I and II. So maybe not the best starting point.

Next
Ys Memoire: The Oath of Felghana – New Game Plus, Explained
Oath In Felghana's New Game Plus works a little differently than you're used to. Here's everything you need to know.