The moused based navigation system in SketchUp is excellent, it allows for quick and efficient modeling and it’s worth getting to know it.
However, if you are looking for a more game like way of navigating in SketchUp Free, use a combination of the place camera tool which allows you to set an eye height then invoke the walk around tool which will allow you to move around your model using the arrow keys, including collision detection.
This would generally be used for test navigating a model or for visualization purposes, not for modeling.
A different way to think about it, as a new game…