I'd make sure the tunnels are all big enough too - some of these toys are far too narrow inside for some hamsters - hamsters come in all different sizes! Is it a syrian or a dwarf hamster? If it's a dwarf most toys are ok, but if it's a syrian most hamster toys are too small and they can get stuck in things, which can be quite stressful if not dire. Rat sized tubes are best for syrians - I get the 10cm diameter ones, but 7cm is ok too.
As Cypher says they like exploring at first. Ours only used to climb the bars when he wanted to get somewhere and couldn't reach it and I realised he needed something to climb on to reach his ledge. Tunnels are different to tubes. A bridge type tunnel makes a level and something to climb over as well as under. Our hamster isn't that interested in toys unless they're edible, but does like tunnels - they feel safe with some kind of roof over their heads I think.
Charlies's favourite thing is this carrot log roll - he spends ages trying to get the carrot out, chews the wood and climbs on it - keeps him happy for ages
http://www.amazon.co.uk/Rosewood-Bor...ds=carrot+roll
He also quite likes this kabob thing if there are treats hidden between the blocks of wood.
Small 'N' Furry Treat 'k' Bob for Small Animals
I changed the ring on the bottom of mine for a standard keyring size, but if it hangs low enough in the cage the ring shouldn't be a hazard, because if they get their feet caught he can't dangle from it if it's low enough. The wood blocks slide up and down and you can stick treats in between them.
Dwarfs enjoy toys more than syrians I think - what type of hamster do you have? Our syrian basically likes sleeping, his wheel, food and hidden food lol! And the odd tube or tunnel, especially if there is food in it.
Sometimes they like to dig tunnels so put some deep substrate in - as much as you can fit in without it spilling over really and you can partly bury a tube with one end sticking out which encourages them to go down it and dig a tunnel. Bendy stick bridges are very popular too. A tunnel and bridge rather than a tube.
I have the medium size one - it's not as big as it sounds when bent over.
http://www.viovet.co.uk/Classic_Rust...nimals/c15326/