subgenre during the late 1970s to early 1980s. These games can overlap with other subgenres as well as space combat games. Tube shooters feature craft flying through an abstract tube, such as Tempest (1981) and Gyruss (1983). There is still a single axis of motion, making these a subset of fixed shooters. Rail shooters limit the player to moving around the screen while following a specific route; these games often feature an "into the screen" viewpoint, with which the action is seen from behind the player character, and moves "into the screen", while the player retains control over dodging. Examples include Space Harrier (1985), Captain Skyhawk (1990), Starblade (1991), Star Fox (1993), Star Wars: Rebel Assault (1993), Panzer Dragoon (1995), and Sin and Punishment (2000). Rail shooters that use light guns are called light gun shooters, such as Virtua Cop (1994), Time Crisis (1995) and The House of the Dead (1996). Light-gun games that are "on rails" are usually not considered to be in the shoot-em-up category, but rather their own first-person light-gun shooter category. Cute 'em ups feature brightly colored graphics depicting surreal settings and enemies. Cute 'em ups tend to have unusual, oftentimes completely bizarre opponents for the player to fight, with Twinbee and Fantasy Zone first pioneering the subgenre, along with Parodius, Cotton, and Harmful Park being additional key games. Some cute 'em ups may employ overtly sexual characters and innuendo. Scrolling shooters Vertically scrolling shooters present the action from above and scroll up (or occasionally down) the screen. Horizontally scrolling shooters usually present a side-on view and scroll left to right (or less often, right to left). Isometrically scrolling shooters or isometric shooters, such as Sega's Zaxxon (1982), use an isometric point of view. A popular implementation style of scrolling shooters has the player's flying vehicle moving forward, at a fixed rate, through an environment. Examples are Scramble (1981), Xevious (1982), and Gradius (1986). In contrast, Defender (1981) allows the player to move left or right at will. Run and gun games have protagonists that move through the world on foot and shoot attackers. Examples include the vertically scrolling, overhead view games Front Line (1982), Commando (1985), and Ikari Warriors(1986). Side-scrolling run and gun games often combine elements from platform games, such as the ability to jump: Contra (1987), Metal Slug (1996) and Cuphead (2017). Run and gun games may also use isometric viewpoints and may