A challenge in AppFront is built out of the same campaign structure covered in the campaigns webinar: an event and a trigger. Take a simple example — "visit 3 times in 30 days, get 100 points."
The event here is a lifecycle event, and the trigger is 3 visits within a duration you define. You can decide whether that duration is a fixed 30-day window from a set date, or a rolling window that starts whenever the customer's first qualifying visit happens.
At the simplest level, this challenge can be built as a single campaign that fires once the full condition — 3 visits — is met, rewarding the 100 points at completion. That's enough if you just need the reward to land correctly.
Where it gets more involved is if you want the customer to see their own progress — for example, a visual "2 of 3 visits complete" status inside the app. To support that, you need one campaign per step (three campaigns for a 3-visit challenge), because each completed step moves the customer into a new group, and each group can be tied to a different badge or image that reflects where they are in the challenge.
The practical takeaway: don't over-build every challenge. It's fine to keep simple, single-campaign challenges running passively as side quests, and reserve the multi-campaign, visual-progress treatment for the challenges you're actively marketing as your main event.