Share your brain games/mental stimulation tools here....

[Doodledangle]

I'm after games I play indoors with my poodle for some mental stimulation and to help along general training (working on 'place' & 'stay' and general manners!).

He loves:
hide & seek with his favourite teddy
finding a treat hidden inside a blanket
sniffing out scattered treats (only just started doing this and he's not great at it but loves it and manages with guidance!)
Tug of war

He likes a lick mat and has a hidden treat tray but it's done in seconds so any other puzzle toy recommendations I can get for Christmas would be great.

Our collie's favourite is treats in a rolled up towel tied into a tightish knot. That takes her a while to get into.

Treats wrapped in newspaper inside a cardboard box she can shred.

Yes, all of the above.
Another game is having 2 or 3 upturned cups (plastic or paper are best). Pop a treat under one of them, shuffle them around and dog has to sniff out and indicate which cup the treat is under. The indication is usually done by either by tapping the cup or knocking it over to get the treat but my pup just sits in front of the chosen one and waits for me to lift it up!
I also sometimes put a treat in one of my hands, hold them both in front of me, and she has to indicate which hand it’s in.

Yes my dog loves this, she adores shredding paper or cardboard.

I did buy a snuffle mat as well and she loves that.

Teach them different tricks like give paw & the other one , fetch different things, roll over, balance a treat on the nose, ...

You can freeze lick-mats and Kongs to get them to last longer.

If he likes treat hunting, a snuffle mat could be a good idea as he'll know when it comes out that it means something good.

During lockdown I taught my beagle a whole load of random tricks - weaving through my legs (both directions), rolling over (both sides), left and right paw, high five (both paws), boop (when he touches his nose to my hand) and spin in circles (both directions) are his favourites and we still work on them now.

We also worked on things like stop, back, go to your bed etc.

Toppls are great, I fill with some of her kibble softened in water, add mash sweet potato and Greek yoghurt then freeze. Just started scent work, hide ball / toy somewhere in the house then find. Also using an old pair of jeans, I hide a ball in each leg and scrunch up then hide in the house, takes her a good age. Frozen snuffle mats with mashed banana and Greek yoghurt. Using part of one meal, I hide around the garden. I play tug with her, using two tug toys and incorporating some basic training - leave, watch, down etc.

There's loads of good you tube etc videos of people training dogs to do various things I love watching them.

If they're really clever then teaching them to do things around the house like fetch items or open doors is great because you never know when they might need to do that job due to an injury etc.

We used to freeze part of my puppies food in his bowl or in a Tupperware and then thaw it until it dropped out and let him chew at it to get his food or a favourite toy, that might be stuffed with peanut butter or something. It helped it take his mind off his teething pain and was a useful distraction.