This seems to be the biggest question I'm seeing from our announcement, so I figured I'd jump in and address it.
Steam programmer and all-around miracle worker Sara essentially managed to combine Ys I & II Chronicles with the earlier fan-favorite PC release Ys I & II Complete, effectively mixing all the best features of both versions. That means it's got the selectable soundtracks and selectable art styles from Chronicles alongside the visual flexibility of Complete (including a greater viewing area, togglable screen frame and support for windowed mode).
Plus it's got a few updates, like the ability to resize the window in windowed mode and have the graphics scale smoothly, as well as the usual complement of achievements and leaderboards.
The achievements are a little different this time, too. Based on feedback received from our Felghana and Origin Steam releases, we've tried to feature fewer incremental achievements and instead go for more once-and-done tasks... but with a twist. Some of these achievements are meant for long-time Ys fans, so their unlock conditions are occasionally kind of like puzzles unto themselves. But if you are a long-time series fan, you can theoretically attain every single achievement on one single playthrough.
The rest of our game announcements are pretty straight-forward, but if anyone has any specific questions, feel free to ask. I might not be able to answer, of course... but hey, I can try!