I've noticed that since M spends most of his waking time downstairs, he almost never plays with the blocks nowadays. Not good! So I freed up some shelf space in the family room and moved the smaller unit blocks there. It seemed to work since he started using the blocks for different games.
And then he built a city for his astronauts and hangars for all the shuttle and the Hubble telescope and a launch pad for the rocket.
He even "planted" a few trees in his city saying that those were apple trees so that the astronauts would pick apples. And he built a planetarium for the astronauts too (can't see it on the pictures though).
Do you see that red structure made of two flat blocks and one cylindrical one? That's the International Space Station. But we ran out blocks before he could build a house for it too.