Border collies tend to be hyper intelligent as far as dog breeds go. You can train them to do anything even when their muzzle is going grey. Be warned that, like most intelligent animals, this means you’ll have your hands full; but the tradeoff is that they tend to have a ton of personality.

Mac (the first dog I remember having) basically trained me to fetch.

Sirius (second dog) came up with his own game; the downstairs of my parents house is kinda like a loop, with a pair of doors leading from the kitchen to the dining room, and he loved to play “go around”. If you closed the doors he’d go around to try and catch you before you could get to the other side; and sometimes he’d fake-out, where he’d run from the living room to the hallway, and then turn around and come back. He would get so excited that he’d actually parkour off the wall to turn around. He also loved it if you just ran away and hid while he was running to the other side of the doors.

Brigid (current dog) loves playing with blankets and sometimes accidentally gets herself wrapped up in them. You can tell she was having fun if the floor is covered in blankets.

Source: mom loves border collies, so we always had one. I like them too because they’re a lot of fun.

Edit: if you wanna push them and see what they can handle, try something like fluent pet and see how many words they can learn. I haven’t tried it with Brigid, but I wish it had been a thing with Sirius; he was so ridiculously intelligent that I bet he would have been able to hold simple conversations with it.