Walk-Off Winner

Walk-Off Winner is an Achievement in Halo Wars that is unlocked when the player uses one of the 6 Major Leader Powers to destroy an enemy's last unit.

It is worth 30 Gamerscore.

Tips
Go on the advanced tutorial, then, when you are in control of Regret, move the Type-30 Locusts away and then kill all of the enemy units outside of the UNSC base.

Play on Release and release the Flood, and then use a leader power to destroy them all.

Play a 1 vs 1 with a friend and get him to buy no units, then use a leader power on his scout unit.

The achievement can also be earned on the campaign level "Scarab" by killing the scarab with a MAC blast.

Trivia

 * The name is a reference to a "walk-off home run" in baseball, in which a batter hits a home run in the bottom of the ninth inning or later, and in doing so adds enough runs to their score to win the game. As a result, both teams "walk off" the field once the winning run is scored.
 * Even though the title says an "Enemy's last unit" you can actually get it by killing an ally's last unit with Regret's cleansing beam.