Don't replace things. Make the new board starting with an empty list and building it up. It'd probably be worthwhile to put in some effort when the program starts to make a "board" in which instead of a color, each item is a list of its neighbors. Then you can map a rule (a function of a list of square numbers) over each square.
Yeah that’s basically what I did if I’m understanding
I get a new variable, set it to a copied version of the current board
Modify the variable using the old board as a reference with the “tiles around x: y:” block
Then for the function I just use said tiles and call them with an if statement that contains the rules
From my knowledge that’s the only way to do it using the if statement for custom rules (what I wanted to make them easy to create)
i did that while building my game of life and it sped it up significantly
because of that it can handle 100 x 100 grids pretty well
That's how you get in trouble!
Use reporter IF 
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