The app takes cues from role playing games by having a system that rewards certain behaviour with experience points, levels, gear upgrades. It also allows you to set custom rewards that you come up with yourself such as watching an episode of your favorite TV show.
The app allows creating a party with other people and go on a quest together. Here, your actions affect not just you, but everyone else in the party as well. If you fail a task, the party loses health, if you complete a task, the party gains experience, etc.
It's hard to understand why the Productive team chose to go with a hefty subscription model to access "all the features" of this app [unlimited number of habits + better reminders]. It's a $14/year for this; there are competitors available without a pricing model like this one.