Headhunter was often referred to as a solid substitute to Metal Gear for Dreamcast owners, being as we/they didn't have Konami's title to hand.
This is a good thing. Not about not having Konami's title, but about the fact that it was regarded as a solid substitute.
Sega probably knows this, and they're possibly improving it right now, damning Snake under their collective breath, and readying the ‘likely-to-be-better-than-Headhunter-and-very-possibly-Metal-Gear sequel’ known simply as Headhunter: Redemption, for E3. The game is scheduled for release on PS2 and XBox later this year, so put on your post-apocalyptic hat to prepare.
As for the other game...
Anyone remember Vectorman? He was a strange green character made out of balls who went around shooting people on the Megadrive/Genesis. We're sure he had a valid reason. Something to do with being on an epic campaign to rescue Gamma 6 from the evil Orbot, Volt. Yeah, that was it.
Anyway, the point is that the third in the series has been announced for PS2 by Sega of America, and will be making an appearance at E3 in its new 3rd person shooter guise.
As with all things E3, expect to see them here, first.