Why did they spell it Scurge instead of "scourge?" Probably because they were trying so hard not to name this "Metroid Fusion."
Does that seem unfair? It shouldn't. Southpeak is obviously a big fan of Nintendo's last 2D Metroid, since they've ripped off the premise (an alien infection that takes over everything in its path), the protagonist (a female bounty hunter in an armored spacesuit, guided by a computer program), the basic mechanism for progress (gradual upgrades make new portions of the map accessible), and the musical themes (minimalist space techno).
What they didn't steal is the infection counter, which has to be periodically reset at save points, and a 3/4 perspective. The combination makes Scurge a lot more action-oriented than Metroid games--exploration takes a back seat to firepower and large hordes of enemies. It's not a bad change, and for newer visitors to the Metroid series, probably not significant. Since Nintendo seems hellbent on ignoring 2D in favor of 3D Metroid offshoots, it's nice to see someone else taking up the slack, and handling it well.