Spy vs Spy was one of those games as a kid that I always saw advertised in computer magazines and on display in shops but at that age I didn't have the first clue what it was about until near the end of the C64's life when I was much older when it became a firm favourite.
Released in 1984 by First Star Software (the makers of the classic Boulderdash) it was actually based on the MAD magazines comic strip characters of the same name (my brother was an avid reader so I knew I had seen the characters before)
The idea of the game was you play one spy versus your opponent and you have to escape an embassy building to make it to the airport before they do before a timer runs out. Like the comic strip, each spy can lay various traps around the rooms to kill your opponent. Each 'death' takes time off of your remaining allowance.
Graphics are average now I think, but could be considered good in 1984 and they do have a cartoony feel. If this game was made 5 years later I think graphically it would have improved. Sound is average at best, and annoyingly repetitive.
There were a couple of sequels released along the same premise - Island Caper & Arctic Antics which were just as good. Definitely still worth a game, and always worth a devilish laugh as you trap your friend good and proper!!