Beat the Terra-tron on the Lost Viking arcade machine.
Kill 50 units with a single Penetrator Round in the “Belly of the Beast” mission on Hard difficulty.
Use the Artifact no more than once in the “All In” mission on Hard difficulty.
Deplete 10 Rich Mineral Fields in a single Melee game.
Complete the “Belly of the Beast” mission without letting a hero fall Incapacitated on Normal difficulty.