What is the Tenacity - Steam Achievements application, how does it work?

According to the introduction of Zoot apps, Tenacity - Steam Achievements is a Entertainment app on the Android platform. There is currently a 1.7.1 version released on Oct 22, 2017, you can see the details below.

Connect your Steam account and track achievements.
Features:
• track achievements for quick access
• see your Tenacity score for every game - calculated based on rarity on achievements you unlocked
• brag to your friends about unlocked achievements and your score
• search and filter achievements
• compare your Tenacity score and unlocked cheevos with your Steam friends

- fixed crash happening to players with no achievements