Habitica - Habitica is a free habit building and productivity application.
Bullet - Share captioned video snippets of podcasts from any app
Coach.me - Coach.me is a coach that goes everywhere with you, helping you achieve any goal, change any habit, or build any expertise.
Box2D - A 2D Physics Engine for Games
Loop Habit Tracker - Loop Habit Tracker (AKA uhabits) helps to create and maintain good habits in order to achieve their...
Matali Physics - Matali Physics is an advanced, multi-platform, high-performance 3d physics engine intended for games, virtual reality and physics-based simulations.