Some advice;
Take a look at the text in the SMB1 header. There are a lot of duplicate tiles (straight lines across Mario etc). You'll only see one in your tile layer, so if
really want to hack that title screen, you'll have to move things around in hex also. What I found is that you can puzzel those pieces into any set of words you want! I hacked the whole thing to say, "River City Mario" in the same, identical style. I never actually edited a single tile, I just rearranged the peices in hex!
You need time and patience, and it helps to have a meticulous nature. I miss ROMhacking... someday I really need to get back into it again.
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