I created this game with Unity3d the popular game engine.
To control time speed, I used Unity's basic time control method "Time.timeScale".
(I purchased additional time control solution, but I didn't use it.)
In my case, Time.timeScale caused problems with Rigidbody. There's some speed sync problem when time speed changes. So I couldn't use Rigidbody.
I used 'Character controller' on player character.
Time Stopper : into her dream download(Android / free) ↓