I've made my own rules since my 5 year oldplays with them. and uses them as "doll houses". I use 16x16 dots plates (no back walls) and make "blocks" with at least 6x6 buildings so he can have room to sit down in the middle. I always use the road pavements as ekstra so he is able to play with veichles as well. I never bought a modular set, due to prices, but rather bought used lego by the weight. Then downloaded instructions and made a moc out of what bricks Ive got. Works wonders and my kid can make wishes for the future buildings/functions the city needs.