Fight screen - user can choose the workout type here
Different enemy types/workputs
Progress screen with user stats
Enemy/workout card
Custom workout creation screen
User performing a push-up workout
User performing a squat workout
User performing a sit-up workout
User performing a pull-up workout
Under Siege app icon

Under Siege

What inspired me

I saw similar apps that gamify workouts and capture your movement with the camera, but most of them only tracked push-ups.

I wanted a full home workout app that could hit the major muscle groups, not just one exercise. So I built Under Siege around push-ups plus squats, sit-ups, and pull-ups: a fantasy RPG where you defend a mountain outpost from various enemies by doing real bodyweight workouts in front of your phone’s camera.

What I built

Under Siege is an iOS app built with Expo / React Native. You pick a workout, face a monster, and fight with the front camera on. Pose tracking counts your reps; each rep damages the enemy. Win and you earn XP, gold, and levels. Lose or flee, and the enemy captures your outpost.

Core pieces:

Camera-based rep counting with QuickPose for push-ups, squats, pull-ups, and sit-ups
Battle loop with HP, sets, rest timers, potions, and progression
Custom workouts so players can fight their own enemies
Onboarding and tips for phone setup and form (lighting, framing, clear background)
Victory sharing via a shareable “enemy slain” card

Everything runs on-device. The camera is used for pose tracking only; workouts and progress stay local.

What I learned

The hardest part was making sure the rep counter works as intended. One missed pull-up or a false count can ruin the entire workout. The detector also has to handle real rooms.
Native bridges matter. Some features needed extending the QuickPose React Native bridge (landmarks for hips/knees) and rebuilding the app. JS alone wasn’t enough.
Scope discipline helps. Changing pull-up logic must not silently break push-ups or sit-ups; shared pose code is dangerous if you treat it as one blob.

Challenges

Pull-ups from a floor camera. Elbow-angle rules that look fine in docs failed for back-to-camera hangs. Walking toward the bar and moving the phone also looked like “reps.” I reworked pull-ups around hips and knees rising together, with gates so camera bob and squats don’t count.

Sit-ups cutting off at the bottom. After the first rep, shoulders often leave the frame when the player lies flat. The counter used to freeze mid-rep. Treating sustained missing pose data as “back on the floor” (after arming) fixed multi-rep sets.

Closing

Under Siege is what happens when you take “just do ten more reps” and turn it into “the outpost falls if you don’t.” Personally, as a gamer who also likes to stay active, this works really well. As you get fitter, your character levels up in the game too.