Woah, forgot these:
+5: Donkey Kong Country - Fear Factory
+4: Star Fox 64 - Corneria
+3: Megaman X - Ending
+2: River City Ransom - Boss Battle
+1: Blast Corps - Beeton Tracks
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HK-47: The very best there is when you absolutely positively have to kill every meatbag in the room. Accept no substitutes!