The 'wallpapers' in question are pirated games made in renpy (python game engine) or rpgmaker (js based), which makes them a really good vector for malware. As

The 'wallpapers' in question are pirated games made in renpy (python game engine) or rpgmaker (js based), which makes them a really good vector for malware. As another commenter noted this is a bizarrely common way for Chinese people to get porn through the great firewall.