I'm going to start a thread about the former Konami flagship just befuckingcause.
It's a great game franchise and it deserves attention even if I'll be the only one posting here. And if that becomes the case...well you guys suck. :<
Did you know that Hideki Kamiya is a big Gradius fan? It's true! He even said that he put a homage to the ending of Gradius 3 in Bayonetta because he thought it was cool as a kid!
The Japanese actually never released a single authentic arcade cabinet of the first four Gradius titles in the US because they thought they'd too difficult. The only time they did release one, was Gradius 3 which was banned from the few arcades after numerous complaints of it's diabolical difficulty.
Some form of Gradius has appeared in nearly every major Konami product from Contra to Castlevania and Zone of the Enders to Metal Gear Solid. Vic Viper was actually a boss in Zone of the Enders 2 and an unlockable 3D remake of the original Gradius was available with the same boss now the protagonist.
Gradius has appeared in multiple anime including Skygirls, Hayate the Combat Butler (funny as shit), that horrible hentai La Blue Girl, and obviously Yu-Gi-Oh!.
Gradius was the first to introduce the options gameplay mechanic in shooters.