Spline is adding some great features like Game Controls and Physics to help with the prototyping process. In this example using a base scene with some objects are helpful in concepting out a potential game design concept that can be shared with a team, client, or as a game pitch.

With how easy it is to make 3D objects and environments; I can see this being a very powerful tool as Spline adds to its tool set to come up with game ideas and test for how fun would it be to play a game idea. I really enjoy making the Golf Cart, adding some new props, and working with the Game Controls to get the Golf Cart to move across the scene with some basic physics.

You can get more involved and add outside textures to flesh out a real scene. This can be a very powerful tool. You can find several examples to use or make your own. There are amazing tutorials for Spline that you can find on YouTube. Alejandro the founder and CEO of Spline does a great job teaching the software and give a variety of ideas of how you can use it more than 3D web interactions/experiences.