Premis: Contra is a series about buff, arian, well-oiled, Rambo-style guys shooting wave after wave of aliens (no homo-erotic subtext intended).
Premis: Metroid is a series about a female bounty hunter, Samus, dead set on ridding the universe of the titular Metroids, soul-eating beasts (she also fights Space Pirates, who like to use the Metroids as their own, creepy little army).
Conjecture: Were Contra to cross over with Metroid, either Samus would have to fight the Contra aliens, or the Contra Rambos would have to fight the Metroids.
Joke: Crossing over random games is funny. Maybe.
 
    

When evil spreads across the land, and darkness rises and the monsters roam. When the creatures of the night make beautiful music, and the things that go bump in the night go bump with greater enthusiasm. When the world is in peril and is in need of a hero...

These guys are, sadly, the best the world can hope for. These are the adventures of the heroes of CVRPG. They mean well, they try hard, and occasionally they do the impossible...

They actually do something heroic.