Hi!
One thing, try adding ice cubes to his water bowl. Do you have a fan or two so the air is moving?
This isn't play but it's still exercise, can you hide treats so he searches them out, put his food in different places including up higher so he has to jump?
Yes!Keep him cool.
Think about lions on the savanna. When it's hot, they lay about under a shady tree or some place cool and wait until evening when it's cooler to become active.
Your cat is doing the miniature version of that.
In the mean time, make sure he has enough cool water and a cool, shady spot to lay in.
You could also put a couple-few ice cubes in his water bowl if he's the sort of cat that likes that kind of thing.
I'll give the putting food in different places a go!
Yes! I've been using the Vaseline trick and it's been great, but I'm not sure how putting treats in random places would work, haha. The ants have had ridiculously good sniffers so far. There was ONE kibble under the sofa after my cat ate and they found it!There might be something here;
How To Keep Ants Out Of Cat Food