Habitica
- https://habitica.com/
- Retro RPG -game mechanics mixed in a real-life todo -list!
- Create, manage and fulfill Dailies, To-Do’s and Habits!
- Gain experience, coins, levels, items etc from fulfilled tasks!
- Create or join in a party with friends - go to quests or boss fights won by real-life activities!
- Use your hard-earned cash on character items and other rewards (customized included)!
- How high/far can you go?
- Most of the content is free; Registration is required.
GamifyRoutine
- https://gamifyroutine.com/game/
- Manage counters and habits and create skills through them
- Use the productive session for extra experience points
- Come up with rewards when your skills level up or when you fulfill a day’s tasks
- Free; No registrations, runs locally in your browser (I believe you need to export data and import to other devices manually if used on more than one device)


In this theme but more mild on the mechanics: Habit-maker
Have you used it yourself?
Started very recently!
This one? https://play.google.com/store/apps/details?id=com.dessalines.habitmaker