In developing my Chrome Extension Serenity, I believe I have hit the perfect balance between keeping users focused on their task while also distracting them with what your app has to offer.
Serenity is a unique game like productivity management tool with website blocking capabilities. The user enters blacklisted sites and a time period for which they are working. This data is then used to create a digital cityscape drawn on a canvas in the extension's popup.
Here is the trick: time in this imaginary city passes in proportion to real life. However, if you visit one of your blacklisted sites, time in this world speeds up. The user is allowed to visit their blacklisted sites, this is not one of those impermeable wall productivity tools.
The reason the user does not want to speed up time in this digital city is because there is a lone worker in his apartment who has the same task as you, finish his work in the time allotted. However, for him, there are 12 hours on the clock. When those 12 hours run out... it's rush hour.
This seems involved but quite honestly it isn't. The methodology I am using is reminiscent to an electric collar for a dog. The first couple of times the user might accidentally visit a site they aren't supposed to, triggering a popup from the extension and an increase in the hours passed.
However, this small jolt should serve as habit builder. The user will eventually remember that they are trying to restrict themselves and potentially begin to care about their progress in the game.
Once this acceptance of the app into the user's daily routine occurs, it is then a question of distracting the user with interesting enough mechanics that inadvertently keep them focused on whatever task they are working on. You want the user to periodically click on the popup on their own will not on your outside influence. If you have to nag and remind the user to click on your app, they never will.
Based on my experience developing apps like Serenity, simplicity is key. You need your idea to be simple yet helpful and alluring. Now that might seem like an unrealistic goal, it isn't. The only thing holding you back from accomplishing this is knowing where and when to stop developing features.
If you keep adding features to your app out of pure boredom, you're not helping anyone. Developing non-essential features sucks the life out of the developer and the user. Things that come out of your brain make perfect sense to you but inherently are confusing to a new user, at least at first. If you bombard a user with a plethora of features, many of which aren't particularly helpful, it will deter them from using whatever you have made.
I created this application because I felt there was a huge gap in the productivity market. Everything out there was either a strict website blocker who forced you into their mold too quickly, or was too lenient and served as more of a meditative service. There is an extremely important yet extremely fine line which all developers need to be wary of when developing an application which is aimed at altering a user's behavior: how to become a part of their routine without annoying the hell out of them.
Quite honestly, I think this idea might be working (at least a little) with those who enjoy using productivity applications. Getting featured on product hunt was a huge hint that people liked what I was doing. App development always involves treading carefully and creating a system which respects the user's boundaries.
In productivity, based on my findings and mild success with Serenity, I believe this involves a very precise amount of distracting the user from what usually distracts them. If you can deter their attention away from sites they visit leisurely and point it instead towards your app and then by association their work, it is a win win scenario.