In my opinion this is a good game. Especially in the concept. The ability to control only the mouse and the appearance of the buildings I liked. The lack of sound and music, I noticed by the end of the game, so maybe you should not add them there. It would be interesting to look at the infinite or long version of the game with blocks capable of building over partially empty space (so that you can build over blocking surfaces if you are raised high enough or above an empty cell).
Suggestions: it would be great in terms of the appearance of the floor to have information on whether it is possible to build in this place. It would also be nice if the icons of the blocks available for construction stand out by sight.
It would be great if you improved the design a bit. Block icons are almost invisible on my screen, I looked at the screen at an angle to see them. In addition, the style of the menu and buttons in the lower right corner in my opinion can be made more aesthetic. No offense, please, I already liked your game, but after the corrections it seems to me the game will become even better.
Thanks for the game, I really liked it. : P