Timeline
All releases are assumed to be Japan-only unless otherwise noted. This isn't a comprehensive list because of a few differences between sources (I made my best guess on those). So please consider it more of a rough sketch of Ys' major releases over the years that's probably bound to change.
1981
Nihon Falcom is founded by Masayuki Kato
1987
(6/21) Ys I released for the NEC PC-88
(6/26) Ys I released for the X1
(8/28) Ys I released for PC-98
(10/8) Ys I released for the FM-7 platform with improvements to the final boss theme
(12/10) Ys I released for the MSX2 with cleaner NPC sprites
1988
(4/22) Ys II released for PC-88 with 4-bit color. Was also released for the PC-98, FM-7, X1
(7/15) Ys II released for the MSX2. Although with slightly lower quality graphics and sound, load times were improved.
(8/26) Ys I released for the Famicom. Considered “Alternate Dimension Ys” and due to hardware issues, map layouts were altered and the final boss was easier.
(10/15) Ys I released for the SMS in Japan (Sega Mark III) with some map changes.
1989
Ys I & II released for DOS, IIGS, PC-98, and X68000 platforms
(7/21) Ys III released for the PC-88
(12/21) Ys I & II released as a compilation for the PC Engine
1990
Ys I & II compilation released for the TG-16 in North America
(5/25) Ys II released for the Famicom
1991
Ys III Wanderers from Ys released in North America on the TG-16 and the Sega Genesis
(January) Ys III released for the SNES in North America
(3/22) Ys III Wanderers from Ys released on the PCE
(6/21) Ys III released for the Super Famicom (SFC)
(9/27) Ys III released for the Famicom
(11/1) Ys III released for the Sega Mega Drive
1993
(11/16) Ys IV: Mask of the Sun released for the SFC
(12/22) Ys IV: Dawn of Ys released for PC Engine
1995
(12/29) Ys V released for the SFC
1996
(3/22) Ys V Expert released for the SFC
1997
(11/6) Ys I released as part of the Falcom Classics collection on the Saturn
1998
(4/29) Ys I Eternal released for Windows
(10/29) Ys II released as part of Falcom Classics II on the Saturn
2000
(7/6) Ys II Eternal released for Windows
2001
(6.28) Ys I & II Complete released for Windows
2003
(8/7) Ys I & II Eternal story released for the PS2; based off of the Complete version for the Windows with a few tweaks
(9/27) Ys VI released for the Windows
2005
(2/22) Ys VI released for the PS2 in North America
(3/10) Ys VI released for the PS2
(3/24) Ys III remake, Limited Edition, released for the PS2 by Taito
(3/24) Ys III (normal edition) released for the PS2 by Taito
(5/26) Ys IV remake released for the PS2
(9/16) Ys VI released for the PS2 in Europe
2006
(1/19) Ys VI released for the PSP
(2/28) Ys VI released for the PSP in North America
(3/23) Ys Strategy released for the Nintendo DS
(3/29) Ys V remake released by Taito for the PS2
(9/29) Ys VI released for the PSP in Europe
(10/6) Ys VI released for the PSP in Australia
(12/7) Ys Strategy released for the Nintendo DS in Europe and Australia
(12/21) Ys Origin released for Windows
2007
Ys Online: The Call of Solum released in South Korea by CJ Internet
(3/10) Ys VI released with Vista support for the Windows
(8/25) Ys I & II compilation released on Wii Virtual Console for North America
(9/5) Ys I & II compilation released on Wii Virtual Console for Europe
(10/16) Ys I & II compilation released on Wii Virtual Console
2008
(3/20) Ys I DS and Ys II DS are released as a revision of Ys Eternal
2009
Ys Online opens beta in Europe and closes operations 11/29 in the same year.
(2/24) Legacy of Ys Book I & II released in North America for the Nintendo DS by Atlus
(9/17) Ys Seven is released for the PSP
(12/3) Ys: The Ark of Napishtim (Konami the Best) released for PSP
(12/24) Ys I & II Chronicles released for Windows
(12/25) Ys Online (Premium Package) released for Windows
2010
(3/18) Ys I & II Seven Set released for the PSP
Sources:
