The app "Everyday Habit Tracker" (desktop and mobile) offers a nice version of the don't break the chain mechanic. It's not bad for exercise and physio or othe

The app "Everyday Habit Tracker" (desktop and mobile) offers a nice version of the don't break the chain mechanic. It's not bad for exercise and physio or other things. I haven't tried it for writing... There is even a "half-done" marker which doesn't give you points but doesn't break the streak (e.g. when you were prevented to do something due to force majeure).