The main section for this category is in the article shoot 'em up, in the section titled Scrolling shooters.

Scrolling shooters are a type of shoot 'em up game that emphasizes fast-paced shooting on a large scrolling playfield with many enemies.

Scrolling shooters are further divided into horizontal (side view) and vertical (top view) shoot 'em ups, but there are also some borderline cases like alternating horizontal and vertical stages in Konami's Axelay.