The crown system is a current feature of Duolingo, replacing both the fluency badge and the skill deterioration mechanic. Unveiled for all users throughout the month of April in 2018, it provides a way for experienced users to get more complex lessons and a more enriching experience through a level system.
Before beginning a skill its crown and circle are in gray. When one finishes learning all of the lessons in a skill, the skill's circle becomes fully colored and gains a Crown Level of 1. If this skill is practiced again, it will begin to accumulate points until it reaches Crown Level 2. There are six crown levels (five in the other version), and the amount of times required to level a skill to the next crown level is the same as the original number of lessons in the skill:
Once a skill has been leveled to Crown Level 5, it turns a golden color and is considered mastered. A mastered skill can be practiced. You can also test out (making no more than three mistakes) to advance to the next level. Once you are at crown level 6, you have a choice of upgrading it to legendary level by passing a certain amount of challenges.
As of 24 October 2019, spaced repetition has been reintroduced to Duolingo. When a skill is at Crown Level 6 or higher, it may "break", requiring a review to put it back together again.
Crowns can also be used to unlock new skills and levels.
In March 2021, Duolingo rolled out a new Legendary Level for iOS and Android users if they didn’t want their skills to crack. Duolingo later changed the verbage and Legendary Levels operate as other levels do including providing a Crown level. For Duolingo Plus users it is free, but for free users you will have to pay 250 gems to be able to reach the Legendary level.
The Legendary Level challenge consists of 4 challenges. If a skill has fewer than 4 challenges in levels 0-5, it will have that many challenges in the Legendary mode. (e.g. if a skill has 3 lessons in levels 0-5, it will have 3 challenges in the Legendary Level as well.
On July 2021, the number of mistakes you were able to make was added.
On November 2021, the time limit was removed. It was later re-added.
Legendary Level became free and became the highest level you could reach without paying gems.
One of Duolingo's problems prior to this feature was the lack of engagement for those who had completed all of the skills of a language tree and wanted more complexity in terms of content. So an A/B test of new Android users began in late 2017. Having been successful in enriching the language-learning experience, it was rolled out to all existing users on all devices in the first week of April 2018.
In March 2021, Duolingo rolled out a new ‘Legendary Level’, with harder challenges if you do not want your skill to crack. Currently available on iOS, Android and PC.
Its arrival was met with mixed reviews, with some users saying it deepened their experience with Duolingo and others claiming it was unhelpful and/or confusing. Some bemoaned the fact that spaced repetition and word lists are unavailable, but the Duolingo staff assured users that these features would be resumed at a later date.