When mine were little I’d take them swimming, or do something real mundane that kids think is exciting - like riding a bus or a train (off peak).
One time we went to the airport just to watch planes take off and land. They loved it.
I was pretty poor back then, so I was always searching for cheap entertainment. Petting zoo’s was another thing we did, and going to orchard’s to pick our own fruit was something they enjoyed as well.
When stuck at home in the rain we used to have “best painting competitions” or dance-off’s. Also just playing good old fashioned board games is good… I never use to make them follow the rules, and would let them think they were tricking me with their sly cheating - I knew what they were up to, but it used to amuse me listening to them giggle because they thought that I was too stupid to know their tricks.
Another time we just got a massive box (big enough for me to fit inside) and we played in that together every day for weeks. I think little kids just love it if you play with them on their level - it’s not so much the activity, but just the time you spend with them.
Hide and seek was also a favourite game. My boys are 12 & 14 now and they still love hide and seek, however the game always starts a bit more spontaneously now, and often in inconvenient places, like at the mall when I’m trying to buy them new shoes or something.
And they pull elaborate pranks on me these days.
It’s a very different dynamic. I kind of miss the little kids I once had. However, I do find teenagers a bit easier to deal with, a part from gamer rage and body odour. These days our activities are things like going to the cinema or doing escape rooms, and getting fruit smoothies seems to be in vogue at the moment, all the while they roast me for being a millennial that chooses to wear skinny leg jeans.