Subscribe to download
Spy x Family Opening as Background Main Menu

ATTENTION!! Simply subscribing the mod will NOT make your background changed...

You will NEED GFSCAPE to open the vpk files extension
GCFScape[download.cnet.com] app for extract vpk file.

After you subbed, open the L4D2 and after you done downloading the mod, GO TO:
left4dead2/left4dead2/addons/workshop/2876854484 OR just search the vpk name that has this thumbnail picture.

Open it with GFSCAPE that you just downloaded and copy the "l4d2_background_01" and replace it into your "left4dead2/left4dead2/media/l4d2_background_01"

IF u want to make it appear all the time then copy it another 4 times for:
"l4d2_background_02"
"l4d2_background_03"
"l4d2_background_04"
"l4d2_background_05"

Then LAUNCH the game and it should be working!!

ALSO FOR MAIN MENU ICON:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2876738915