No MainsG 50

This can be obtained fairly easily by starting up a 1v1 Skirmish match against each of the civilizations and using the tuck tuck tuck cheat as soon as the match starts.

You can choose any map though I'd recommend either Alaska or Borneo due to the small size of these maps.

Check to ensure that Extreme is selected as the difficulty for each match.

Now once the match has started, press Enter to open the chat box. Then type tuck tuck tuck and press Enter to spawn the monster truck near your town center. Simply move the truck over all enemy units and buildings to win.

Rinse and repeat for each civilization.