Splinter Cell director says Metal Gear Solid's "clear rules" showed the team "how stealth should be done" and "set the rules for any stealth game"

Splinter Cell: Chaos Theory.

Ubisoft developers working on the original Splinter Cell borrowed a thing or two from Metal Gear Solid's influential, stealthy 'action espionage' way of doing things.

Hideo Kojima's 1998 action-adventure, Metal Gear Solid, by no means invented the the act of sneaking around intricate, zig-zagging levels all while unarmed, but it did somewhat popularize the stealth genre in general. Metal Gear Solid's complicated anti-war storyline and sometimes indulgent, always ambitious cutscenes are probably what garners the most attention nowadays, though the game's careful infiltration is what snuck into other series.