Pick up 30 coins in a row on a single level without letting any disappear.

Start a character in multiplayer or customize a character in single-player.

Make the final assault.

Defeat an old adversary.

Send a warning across the galaxy.

Dispatch 10 probes to retrieve people or resources in Reaper territory.

Call down an orbital strike.

Sabotage a dreadnought.

Establish or rekindle a romantic relationship.

Evacuate a scientific facility.

Explore a lost city.

Defeat a Harvester.

Defeat the last zombie in a level with a lawn mower.