The PC version saw a limited physical release, primarily in Poland, Russia, and the Czech Republic . This makes finding authentic, English-language serial numbers difficult.
If you are looking for codes to enter (via the Clubhouse "Extras" menu), use these: Ultimate Courage (Invincibility): 4449 Double Damage: 9991 Big Head Mode: 2654 Chipmunk Talk: 3293 Slow Motion: 1954 scooby doo and the spooky swamp serial number
Are you getting an or is it a physical prompt during setup? Did you buy a physical disc or a digital copy? SCOOBY-DOO! - AND THE SPOOKY SWAMP - (NTSC-U) The PC version saw a limited physical release,