[Jeir]

Hamsters seem to have a mental age comparable to a human baby/very young toddler, at least from what I've observed with mine. They're not super intelligent, but recognise their humans/safe places, and can figure out very basic puzzles. In the wild, their focus would be on travelling to find food, digging deep burrows, and avoiding predators. Domesticated hamsters don't have to travel far for food, or avoid predators, and often their substrate isn't deep enough to make big burrows, so they need more mental stimulation in other ways.

For my hamster, I have a few toys in his cage to help, all of which are 'how to get treat' focused, as hamsters are very food motivated:
- A pine cone hanging from the ceiling, in which I can put treats in. It's only within reach if he stands on his back legs, so he has to work out how to spin/tip the pine cone to get the treats.
- A forage toy made of a low cardboard box and some cut wood branches. I bought mine from Pets at Home - 'Woodland Small Animal Snuffle Forest Activity Toy' - but you can make your own if you're fine with DIY. The wood pieces fit snuggly, but can be pulled out by a determined hamster, and you can put treats in the gaps to encourage it.
- The standard toilet roll tube toys. Take a toilet roll tube, cut slits into the ends so you can fold them in, put treats inside, and the hamster has to chew their way into it to get the treats.
- Scatter feeding! I usually just sprinkle treats he's piled up in the open around his cage to re-find and re-pile up.
- Coconut hide/ceramic salt pig/ceramic hamster hide filled with tissue (which can be carried back to his nest as extra bedding) and treats put right at the back/mixed in so he has to search. Straw/hay could probably also be used.
- Very simple sliding puzzle toys (from Bucatstate on Amazon). It came in two pieces; one a small triangle with a swivel cover over a recessed hiding place, and another larger one with a swivel cover, and two sliding covers. Treats go in the recessed parts, and the hamster has to move the covers out of the way to get the treats. BUT, this one comes with risks (hamster might get foot stuck; the covers aren't tight, but the risk is there), so please be aware that it might not be suitable for your hamster (or any hamster other than mine).

Sadly you might still have to set him up in a tank style cage; one made of glass so he can't chew his way out. Or, if you have the funds and would prefer to keep him in his current cage, you could see about getting acrylic screens to cover or replace the bars (I highly recommend Viking Laser for this).