Thank you! If you leave a rating here and feedback by clicking the link in the game's main menu that would be highly appreciated! I created the game in a way where I had level editor class, that I inherited into level class, co I could create levels quickly without any coding. Level 1-4 are here just to teach the player the mechanics. I had some general ideas on levels during coding the game, so I had all levels done probably in 10 hours (yeah ideas are the hard part) :D. Then I put them in order to keep game fresh and puzzles (hopefully) challenging.
Regarding problem you are describing, if you mean block selection - yeah it's far from perfect. This was my first 3D project ever, so most of the stuff here is completely new for me and I was unable to find a perfect solution. I hope I'll become better next try!
EDIT: Thanks for tip about z-fighting, I'll check it!