I have a tower, I sell it to put in place of it a better tower, how do I destroy it and verify that the site occupied this tower is free.
Why not have all tower in a single sprite Frames or animation and have if sell change the frame or animation to the empty slot. and have a variable that tell which tower it is. Instead of creating mulitple tower just have it all in one sprite and place it on the board.
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It makes sense what you said, I will try to do here.