mitsuru yaida and hideyuki suganami were programmers on contra 3. suganami made alien soldier//mischief makers//sin & punishment. and yaida was the project lead for gunstar heroes. it technically is a response to gunstar heroes, but it's more like the influence of design overhead since contra 3 was one of suganamis first projects in general, so they ended up being similar as contra 3 was designed with gameplay density in mind-- something everyone at treasure goes on record stating is one of their most important values some way or another in interviews.