The term "Silver Strike" is a term copyrighted by Global Gaming which was purchased by Anchor Games which merged with IGT. It is reserved for strikes produced under their program. This is the same definition adopted by the Chapter Officers for the Silver Strike of the Year competetion. Under that definition, the slot tournament and commemorative pieces produced for casinos, such as this piece for Imperial Palace, can not be considered silver strikes.

But, of course, none of that matters since we all collect what we like and to heck with definitions.