[LunaTheHamster1]

It can be a bit of both. Depends on the hamster, some hamsters may be scared of a big open space so you may need to add things in the space. I can do both with my hamsters, sometimes i just let them run free in the hallway where there is just my shoes to run around and over, and a curtain to run behind (be careful they can't climb it!!!), other times I will add a load of items for them to run around in/over and a wheel.
I also use my conservatory in the summer which is full of my yoga bolsters/cushions which they like to hide/run around in. Again, I also add their own things and a wheel.
In the winter I use a big plastic storage box which is full of toys for them.
Experiment, I would say if your hamster moves around slowly, close to the floor and doesn't relax, or stays closely to the sides they may need more things to cover the floor space up a bit.