AppFront's challenge library covers five distinct challenge types. Each one is built to move a different number, so start by identifying what you're actually trying to fix before picking one.
Frequency / visit challenges — build a repeat-visit habit, e.g. "visit 3 times in 30 days." A good starting point if you want more regular traffic, especially during a specific day part.
Spend challenges — raise average ticket by rewarding a spend threshold, either a single check total or cumulative spend across a window. A good starting point if your KPI is ticket average rather than visit count.
Product / menu challenges — cross-educate guests on your menu by requiring purchases across different items or categories, breaking customers out of their usual order.
Day-part challenges — target a specific slow window (a lunch rush, a late-night slot) to build traffic there instead of relying on a blanket discount.
Multi-step / event challenges — combine several of the above into one challenge with a clear start and end date, marketed like a real event (e.g. a 30-day restaurant challenge or a VIP challenge).
Each of these is covered in more depth in its own article — this one is meant as the map of what's available before you start building.