An example of an achievement score, and where to find it on a Habbo's infobox (in the yellow square.)
Your achievement score is the amount of points you have earned from unlocking Achievements. Since new achievements are introduced regularly, the amount of your achievement score can go up almost never endingly. Some people are known to have 200,000+ achievements scores. Although these people usually boosted their score by using Facebook and adding extra points to it, although this feature has since been removed.