Interlocking building parts that snap together and can be placed in a grid. Like how Valheim does it. It also has 22.5° and 45° diagonal pieces that fit well together. There are also a wide variety of pieces that can mix and match to create different aesthetics. The controls are also very intuitive, it only takes a short amount of time to understand the mechanics.

A contrasting example would be No Man's Sky. While it too has a nice variety of pieces that can interlock together, the controls aren't as good. I frequently end up snapping to the wrong edge unless I've got a completely flat floor with all identically sized wall pieces, and even then it sometimes doesn't let me place things where I want them to go. If NMS had the same build controls as Valheim, I'd be much more content with the (otherwise great) game.