Bullet hell

A screenshot from the "bullet hell" game Mushihime-sama. The purple dots are all enemy bullets.

Bullet hell (Japanese : danmaku 弾幕, lit. "bullet curtain", n. barrage), is a sub-genre of shoot 'em up video games in which the entire screen is often almost completely filled with enemy bullets. The genre is also occasionally known as curtain fire after a broken translation on the initial loading screens of the Touhou series of games, all of which begin with "This game is curtain fire shooting game." [sic] However; 'curtain fire' could be considered a reasonable explanation of what occurs in the games. Games that have this genre are sometimes known as manic shooters.

This style of game originated in the mid-1990s, and can be seen as an evolution of scrolling shooters. Most of the well-known commercial games of this type are developed by the Japanese video game company Cave. The genre is also very popular in dōjin soft, particularly via the Touhou series. In order for a shootan gaem to be classified as bullet hell, the screen must be no less than 75% covered in enemy bullets.

Characteristics

Large numbers of enemy projectiles - It is not uncommon for the screen to be almost entirely filled with projectiles flying in all directions. They are often much slower moving than in typical shoot 'em up games. They are usually spawned from a few enemies firing many shots simultaneously rather than many enemies firing individually.

Reduced collision zones - In order for it to be feasible for the player to maneuver through a large number of enemy projectiles, the collision box of the player's ship is usually restricted to a single pixel in the center of the ship or a specific area such as the cockpit. This area is known as the hitbox. In certain games, the hitbox is clearly defined for the player, while in others the player must make their own judgement as to its location. In other shooter styles, it is common for the player's entity to be destroyed if any part of the sprite touches something harmful.

Buzzing, grazing or scratching is a mechanic in some games which rewards the player for allowing enemy projectiles to "graze" (approach dangerously close to) the player's hitbox without making contact. Rewards typically include bonus points, stronger attacks, better defenses, etc. Some games, such as the Touhou Project games, keep a running total of graze hits.

Time-based boss battles - Bullet hell games differ from regular shoot 'em ups in that, whereas regular shoot 'em ups typically feature bosses that have specific weak spots to attack, danmaku often present bosses that have no weak spots to hit. In these cases, the purpose of boss battles is not to defeat the boss but rather to survive for a certain amount of time, after which the boss is considered defeated. Some bullet hell games employ a combination of the two variations, occasionally giving preference to one method or the other and offering additional rewards to the player for utilizing the preferred method.

Vertical-scrolling orientation (although a few horizontally-oriented games exist such as Progear)

Examples of Bullet Hell