Firstly, thanks for the positive feedback! It’s great that you are enjoying CastleMaker, especially this early on. I will be sure to continue on this project for a while.
For the problems of middle clicking to place enemies, would a Ctrl+Left Click work or something similar? Secondly, about importing custom sprites, would you prefer dragging and dropping the sprites into a folder or an in game editor? Both could work well, but I could go both ways. In game means that custom sprites will always work, but might need to be remade every time the game isn’t opened. For external, it would be more of a hassle to import them (naming conventions, correct dimensions, etc.), but it would give more flexibility and be easier to reimport.
Once again, I want to thank you for your feedback. It helps improve the game and keep me going.