Here is an idea for the littlest customers of lego duplo
Build your village in one season and then simply turn your creation around to see it in another one.
Each piece colored half in winter cold colors and half in summer greens.
So you build both seasons at the same time!
The set might include Santa Clause and farmer.
The scenery setting would benefit from extra blocks made as gift boxes or apple harvest.
It also makes the time of the game longer. After building the village your child switches to another kind of activity- role play, story -telling, etc...
Lego meets puzzle. I don't think any other building sets can do that. Only lego. Because it's box-shaped pieces allow to color them in 2 colors with defined edge and angle.
And the most important for this age: