all I did was reducing the number of colors with photoshop cs5. it's almost automatic, I just have to choose some colors by hand that I really want to appear. I also do not have the name of the game the bg is from, the only thing I know is that it is somewhere in spriter resource
i can guarantee that there are only 16 colors, haha. I do not have my pc right now, but next week I'll send you the tileset. also, the transparency is the best bug ever. i have no idea how it ended up like that.