As above, hard to disagree. You could write a book on this topic. No one can tell you the exact way to do an entire game system.
But perhaps you do not want an Entire Minecraft Voxel Pro+ Notch Edition Certified but only some simpler blocks stacking. This would still require too much script to post here. Do have a look at Hierarchical Instances Static Meshes (HISM). They’re speedy enough to create something usable; less than 5 mins of work gives me this:
Break it all down into small pieces and work on those. If you have a more specific question, do tell. See if you can figure out how to attach blocks to the sides of other blocks. The above only stacks them up vertically.