have multidirectional movement. Bullet hell is a subgenre of shooters in which the screen becomes crowded with complex "curtain fire" enemy patterns. It is also characterized by collision boxes that are smaller than the sprites themselves, to accommodate maneuvering through these crowded firing patterns. This style of game, also known as "manic shooters" or "maniac shooters", originated in the mid-1990s as an offshoot of scrolling shooters. A Reverse Bullet Hell is a subgenre characterized by the player character collecting or unlocking abilities and attacks whose visuals overlap and clutter the game screen as the game progresses. They also share a feature of many enemy characters, commonly called "hordes," walking toward the player from off-screen. Trance shooters A small subgenre of shooter games that emphasizes chaotic, reflex-based gameplay designed to put the player in a trance-like state. In trance shooters, enemy patterns usually have randomized elements, forcing the player to rely on reflexes rather than pattern memorization. Games of this type usually feature colorful, abstract visuals, and electronic music (often techno music). Jeff Minter is commonly credited with originating the style with Tempest 2000 (1994) and subsequent games including Space Giraffe, Gridrunner++, and Polybius (2017). Other examples include the Geometry Wars series, Space Invaders Extreme, Super Stardust HD, and Resogun. History Origins The concept of shooting games existed before video games, dating back to shooting gallery carnival games in the late 19th century. Mechanical target shooting games first appeared in England's amusement arcades around the turn of the 20th century, before appearing in America by the 1920s. Shooting gallery games eventually evolved into more sophisticated target shooting electro-mechanical games (EM games) such as Sega's influential Periscope (1965). Shooting video games have roots in EM shooting games. Video game journalist Brian Ashcraft argues the early mainframe game Spacewar! (1962) was the first shoot 'em up video game. It was developed at the Massachusetts Institute of Technology in 1961, for the developers' amusement, and presents a space battle between two craft. It was remade four times as an arcade video game in the 1970s. Emergence of shoot 'em up genre (late 1970s) Space Invaders (1978) is most frequently cited as the "first" or "original" in the genre. A seminal game created by Tomohiro Nishikado of Japan's Taito, it led to shooter games becoming prolific. It pitted the player against multiple enemies descending from the top of the screen at a constantly increasing speed.