Some of the adventures above were designed intentionally as sequels (including the Island of Dr. Apocalypse and Assassin). Others built on earlier works. For example,  the Tarot Masters from Opponents Unlimited are expanded in The Pentacle Plot. The characters with ties to the "Dominion Day" adventure from Alone into the Night appear in Super-Crooks & Criminals. A character from Iridium Con is related to a character in Pre-Emptive Strike, and the organization G.I.A.N.T. appears in both adventures.

No contest. Destroyers/Apocalypse was THE most formative set of adventures in my entire gaming history.