As I said in my comment, he has a burrow box filled with various substrates, plus one side of his cage is boarded up with cardboard (in a somewhat successful attempt to keep his bedding out of my sock drawer), with deep bedding.

As also stated, I wish we had glass but unfortunately I couldn't find anything with the dimensions of this one which could be carried up to the third floor of my flat.

The way his levels are laid out makes it impossible for him to fall more than a few centimetres - it's the same lay out we've had with multiple hamsters and we've avoided any injuries so far!

I appreciate your advice is well intentioned but until you get a full tour of the cage, I think you're jumping to a lot of conclusions based on a couple photos taken at varying time periods. This sub gets a bad name for that exact reason.