The Blockheads Wiki talk:Image guidelines
Why we use 160x160
Block images can be reduced to 16x16 pixels. Scale it up by 10, and you get 160x160. Items in the inventory can be reduced to 20x20 pixels. Scale it up by 8, and you have 160x160.
Theoretically, we could use any number. But then the pixels wouldn't be square. The only ones where the pixels are square are multiples of 80. Since we display our large images at 140x140, (why is a mystery) 160 is the least common multiple of 16 and 20 that is greater than 140.