@xunshu as far as I have been able to tell, "Where's Waldo/Wally" is still covered under British Copyright law.
So Pimax might not be able to legally use the "Where's Pimax" even with @aesopfabled's consent.
The rights holder(s) to "Where's Waldo/Wally" might be able to file a lawsuit against Pimax if you use it. Now if you got the rights holder(s) permission then you should be able to.
International Copyright law is a messy area...