First ever stealth game - NOT Metal Gear!

[A.G.]

It's true! A game 6 years before Metal Gear 1 utilized many of the stealth elements the MG Saga became famous for:

en.wikipedia.org/wiki/Castle_Wolfenstein

[The Mad Jackyl]

Eh, like the article states, prototypical. A forerunner, I'd say, but not a true ancestor. Like saying the Shagohod is a full-on Metal Gear (very Metal Gear-like, a prototype I'd say).

[A.G.]

Still though, the stealth genra began with this game, not Metal Gear.