Oh, the nostalgia. These wallpapers found here are from various games. Chrono Cross, Suikoden, Shining the Holy Ark, Breath of Fire...
All of those are self made and have been released online between 1999 and 2000. They also all have a screen resolution of 800x600 which barely any of the current gen computers have set as default. Yet, if you like a trip to nostalgia, feel free to download them!