This app shows the special relativity theory by Albert Einstein. With this Einstein Train you visually observe
Time dilation. Depending of your position (Camera position) you either see the red clock working as usual or the green clock working as usual.
You also can observe
Depending on your position either the train looks as usual or the station looks as usual.
All depending on your speed.
Theres also an option that demonstrate the velocity addition formula with an cannonball
An explaining documentation isn't online at this moment.
Theres also an app demonstration length constraction with four Einstein Clocks.