I've been using Habitica for a few years now and while I love the idea, from a technical standpoint the mobile app is broken. It feels like something you would have on your phone back when touchscreens were a new thing. The most annoying bugs are: party screen not updating after you accept a quest invitation so you're not sure if you accepted it, spamming buffs sometimes reduces your mana without actually applying the buff and party chat not updating (have to restart the app to see new messages)