We're already giddy over the pseudo-retro goodness that is Contra 4 for the Nintendo DS, but this might toss it into game of the year category. Konami has announced plans to celebrate the franchises 20th anniversary with a slew of in-game bonus content that's making me drool all over myself as I type.

• 20th Anniversary Virtual Museum – this museum provides a virtual history of the Contra franchise since the early 80’s, including box art, screen shots and information on every version of Contra from the US, Japan and Europe. The museum also features an unlockable gallery of bonus art.
• Unlockable Games – The NES versions of the classic Contra and Super C are now unlockable.
• 5 unlockable characters, including the Probotector from the European version of the Contra games
• 2 unlockable digital comic books from longtime Contra artist, Atsushi Tsujimoto
• An interview with noted Contra Producer Nobuya Nakazat

Content like the unlockable versions of Contra and Super C had been rumored in the past (having appeared on a GameStop sell sheet a few months back), but had long been written off as too good to be true. With that content's confirmation, in addition to all of the other stuff they're cramming into this cart, this sounds like a Contra fans wet dream.

Don't think about that too hard. 

[Source: GoNintendo]