I have decided to try a deep dive into Kingdomino because it is simple enough to easily analyze and (more importantly) my son enjoys playing it.
As a skillbuilder, Kingdomino excels at spatial reasoning. The gameplay involves laying tiles to most efficiently build sections of land. The rules as written explain that players must build a 5×5 square using the tiles. Any tiles that do not fit in the 5×5 square must be discarded. I changed the rules to better fit our family. Instead of discarding tiles, any player that ends the game with the 5×5 earns an extra ten bonus points. I prefer to reward players for doing well instead of punishing them for making mistakes.
The bonus goal of a 5×5 square adds extra strategy to the game. It may be worth it to ignore the ten extra points in order to build a more profitable but awkwardly shaped kingdom. Also, young children are less likely to get frustrated if they are not penalized. My son knows he should build his kingdom as a square. However, he is still developing the necessary spatial reasoning and forward thinking. The 5×5 is a goal to achieve, but missing the goal is not too bad. As we play more, I imagine he will get better at seeing how to place his tiles and create the perfect square.
As for Kingdomino as a game, the houseruled ten bonus points matter. In nearly every game we have played as a family, the winner needed the points to win. Perhaps ten is too many, and if I were more interested in a perfectly balanced game I would experiment with different amounts.