(re: Police Quest Collection ver 2)
as far as i know, these games were released with copy protection. i have this version of the collection too (got it used at a thrift store) and the copy protection is in place for PQ2 (the only one i’ve played off that CD). i’m glad the code from the PQ1 remake worked for you, others have said that those codes didn’t work for the collection.
the link below has manuals / copy protection for games 2 and 3 for download.