Vanguard

Vanguard is the first scrolling shooters ever made that allowed scrolling in multiple directions, and is additionally notable by being the first shoot 'em up where a player can shoot in four different directions.

The Gond has been terrorizing nearby space colonies with its periodic raids of destruction. The time has come to put an end to his reign of terror. The player has been selected to pilot an advanced fighter ship with high offensive capabilities, and must enter the cave inside the asteroid where the Gond makes his home, and safely fly through every zone; the Mountain Zone, Rainbow Zone, Styx Zone, Stripe Zone, Bleak Zone, and the City of Mystery (aka Last Zone) where the Gond is rumored to reside. The player must take the Gond out, and succeed in the mission. If unsuccessful, the colonies will be doomed.