From the homescreen, swipe two pages left to get to Help & Options. Under "Puzzle language" change it to another language like Arabic which has few players. This will quickly restart the app. From there, just play through a full round. If you join a game mid-round, you need to finish that one and complete the next round. Basically, you need a full 2 minute long round for the achievement.
You will also have a good chance of netting "You're on top of the world" achievement, "You're good, real good" achievment, and "Better than half" achievement in one round if you score high as there are fewer players in this lounge.