Gunstar Heroes[b] is a run and gun video game developed by Treasure and published by Sega.

The game's premise is centered around a pair of characters, the Gunstars, in their efforts to stop an evil empire from recovering four powerful gems.

Following an unwillingness of Konami to embrace their original game ideas, the team quit in 1992 and formed Treasure to see their project through.

It helped establish Treasure's place in the industry, and introduced several design conventions which would become characteristic of their later work such as large bosses and a unique sense of humor.

Gunstar Heroes is a run and gun game played from a side-scrolling perspective similar to Contra.

[6] In addition to firing their weapon, the player characters can pull off a series of acrobatic maneuvers including jumping, sliding, and grabbing and throwing enemies.

[4] In 1991, several Konami employees led by programmer Masato Maegawa began holding planning sessions at coffee shops for an original game.

[9] Maegawa and his team were growing frustrated with the industry's reliance on sequels to established franchises and console conversions of arcade games to generate revenue.

[9] They felt Konami had fallen into this pattern as a large company, growing reliant on sequels in their Castlevania and Teenage Mutant Ninja Turtles series.

[9] Maegawa was interested in the platform because of its Motorola 68000 microprocessor, which he felt was easier to program for than the Super NES, and more powerful.

[9] The staff was split in half to work on both Gunstar Heroes and McDonald's Treasure Land Adventure in parallel.

[9] Maegawa got approval to add a Treasure logo when the game booted, which he felt was a rare opportunity for developers to get in that era.

[8][10] Programmers Mitsuru Yaida and Hideyuki Suganami previously programmed Contra III: The Alien Wars (1992) for the Super NES at Konami.

This led them to consider it more suited for action games and the sophisticated graphical effects they were looking to create.

[8][9][10] The team implemented heavy visual effects in an exercise in design experimentation (not an effort to push the hardware).

[9] The team approached Gunstar Heroes with an "anything goes" concept, that led to many ambitious ideas being implemented into the final game.

[8] Maegawa claims the game could have never worked on the Super NES because the boss animations required expanded computing power.

[9] The standard enemy characters, designed by Han, were drawn on the screen by combining a top and bottom sprite, allowing for more animation patterns with lower memory usage.

[8] Han was inspired by the game Mazin Saga: Mutant Fighter (1993) to program the enemies manually rather than with mathematical algorithms.

Senour did ask Treasure to change one boss character because it looked too similar to Adolf Hitler.

[22] Gunstar Heroes was originally not considered for the series because converting the game's backgrounds into a layered 3D effect was thought to be impossible, but these perceived problems were later overcome.

[40] Mean Machines Sega wrote that Gunstar Heroes was setting a new standard for action games on the Genesis, calling it "a stunning title both in appearance and the gameplay it offers.

"[31] Mean Machines Sega agreed, commending the variety in level design and the "frantic, high-density blasting mayhem.

"[34] Sega Force believed the game's variety prevented it from falling into monotony, and instead, reinvigorated the platform genre.

[34][33][30] GamePro called Gunstar Heroes "chaos in a cart" with "murderous action, excellent controls, and imaginative game design.

"[33] The game's two-player cooperative mode was praised,[31][30] although some felt there was too much clutter on the screen to tell the player characters apart.

[42] Mean Machines Sega agreed, thinking that the graphics remained true to the 16-bit original despite greater system limitations.

"[46] USgamer wrote that its chaotic and brash nature made it the "quintessential classic-era Sega game" in contrast to the more gentle offerings from Nintendo.