To discuss the Timeline Editor, I will have to give you a little refresher about the Scene Selection Bar.

Scene Selector Bar can be seen at the bottom part when you go to the Game World.

The +Add button is one of the ways to add a new scene. Clicking this will let you add a blank scene.

Another way to add a new scene is by pressing D on your keyboard. Pressing this will allow you to duplicate the current scene selected. I prefer using this instead of starting out from a blank scene. 

You can also mute a scene by pressing M on your keyboard. This will hide your scene when you preview your game.

You can press S (which stands for Solo) if you want to preview a specific scene. And then S again to re-enable the scenes.

Now let us talk about the Timeline Editor. If you press the ^ button beside the +Add button, It will display the Timeline Editor window. This will easily show you all the scenes and how they are arranged.  

The value shown below is your game distance. This means that your start scene will start from 0 to 1000 game distance, and the rest follows. 

You can also stretch a scene by dragging and dropping them as shown below.

The illustration below means that the start scene will play from 0 to 1000 distance, then scene 1 will play from 1000 to 2250, then from there, Buildbox will randomize scenes 1, 2 and 3 from 2250 to 3000 game distance. 

You also have the option to align or randomize scene by clicking on edit.

Selecting Randomize Scene will stack scenes one on top of the other except from start scene. This means that Buildbox will randomly choose one scene after another through out the duration of the game.