The game is really cool and fun to play. It has nice aesthetics and solid sound effects. The music loop can become a bit irritating over time.
It would be helpful to have some indication of where enemies are or when they’re coming. At the beginning, I wasn’t sure if an enemy was going to appear or not. I initially thought the game was incomplete and only had the construction part.
Small thing but having the mouse used for both construction and shooting feels a bit awkward, as you have to shoot to build. Maybe separating these into different scenes, such as a fight scene and a construction scene could improve the experience (if you plan to continue working on it).
Splitting resources might not have been the best choice. If they were kept together, the player would have to make decisions between defense, speed, and offense. Which would add a strategic element to the game.
The fights are definitely fun but end a bit too quickly, and collisions can be quite harsh. Perhaps the blocks need more durability. Also big enemies are really tough ;).
I’m sure the game has the potential to be a lot of fun with a few adjustments.
Good job!