Wild Guns/WMG

The bosses of the four selectable levels are somewhat based off the four classic Greek elements (Earth, Fire, Wind, Water)

 * Desolation Canyon- Fire (tank attacks with a flamethrower and incendiary missiles)
 * Gold Mine- Water (it's a Giant Enemy Crab)
 * Armoured Train- Air (the jetpack dude flies)
 * Ammunition Depot- Earth (it's based off a snake or worm, something which lives in the ground/under a rock)