| Top Secret was the name of a role playing game put out by TSR (the makers of Dungeons and Dragons). It was designed by Merle M. Rasmussen and Al Hammack in the late 1970s, as a RPG involving espionage set in the contemporary era. A second edition was released in 1981, and a totally revised version came out in 1987.
Characters play secret agents in the employ of The Agency, who in each module are given missions to complete (either as assassins, investigators or confiscators).
After completing missions agents get experience points which will put them up levels and make their characters somehow more powerful.
So you can already see that it is imitating some of the mechanics of Dungeons and Dragons. Except there are no dragons or magic, and it feels a bit odd when eight characters are on a secret mission to raid a Soviet embassy like a posse of paladins and barbarians tramping through some hobgoblin-infested catacombs in search of treasure.
Amongst the modules put out include
Sprechenhaltestelle A mission without a plot - agents just visit a seedy neighbourhood full of Euro trash bad dudes.
Rapidstrike! Some master criminals have invented a psychedelic drug on a desert island and you have to stop them taking over the world.
Operation Orient Express Another plotless mission set on a train.
Lady in Distress A Mediterranian cruise ship is hijacked by criminals seeking to capture a biological weapon.
Fastpast Agents must help some Soviet bigwig defect out of Hungary.
Ace of Clubs Agents must stop some bad guys infiltrating a secret spy school in upstate New York.
Seventh Seal A nuclear bomb is timed to go off somewhere in Los Angeles. | 
