var/obj/overlays/S = new(usr)
S.icon = 'turf.dmi'
S.icon_state = "gasmask"
usr.overlays += S
The code above works in a way.
It adds the gasmask etc...
...but it adds the gasmasks as a UNDERLAY, while the code says it must do it as a OVERLAY.
How do I fix this???
You must set the object's layer above the mob's layer;
~>Volte