Successfully complete the indicated task in Planet Superstars mode to unlock the 
corresponding stage:

Alex Kidd: Successfully complete "Get A High Score!" in the "Space Harrier" 
stage. 

Outrun: Successfully complete "Hit Justice Shots" in the "Virtua Squad" stage. 

Space Harrier: Successfully complete Tournament Singles in the "Space Channel 
5" or "Virtua Squad" stage. 

Virtua Squad: Successfully complete "Hit The Big Zombies!" in the "Curien 
Mansion" stage.