We recently were in a position to make our own fun and when the busy book did not inspire we had to use our own ideas.The kids' grandma got the ball rolling by doing the "memory game" where you present a tray of objects that you get to see for a short time and then you look away and write down or tell (if you can't write yet) what you saw.
We got into play clay big time. There were no limits on that one. Really, none. Jumping fish, and a blueberry tree and a giraffe that can bounce are proof of that.
Then, with a start, I realized that there was the capacity to play Jenga in the house (and all the pieces were in the bag!!) We had been sadly overlooking it all this time. It quickly got turned into another version, but cool, all the same.The best, most enduring activity was the TASTE TEST. That idea kept on giving. Raisins, pepper, salt and cookies and milk. Not a lot of mystery there, but fun to set up and come up with new things to try.