Street Fighter II, the World Warrier (2021)

Summary

Dec 23, 2021 Street Fighter II, The World Warrier This article is part of a series about Street Fighter II and the CPS-1. It is recommended to read the previous entries before reading this one. The embarassing typo One of my favorite anecdote about Street Fighter II is Akiman's account of an issue discovered shortly before shipping. Just three days before the deadline, I discovered something horrible. I had made a mistake with the subtitle “World Warrior”, mis-spelling it “World Warrier.” - Akiman, Lead graphic design on SF2 (translated by Shmuplation) A recreation of the problem. Ouch! To fully understand the issue, we need to dig into how the arcade hardware works. The CPS-1 is a super tile drawing machine. It can draw a lot of tiles but cannot alter them. They are taken from the GFX ROM as they are and sent to the screen (although they can be flipped horizontally or vertically). The GFX ROM and the 68000 instructions ROM as burned separately. The problem Akiman describe is that the GFX ROM had been burned but he could still make changes to the instructions. But how could he fix the mistake if the artwork was set in stone at this point? Now I can safely tell this story too, but we actually didn’t discover it until several months after all the sprite work had been done. Since the logo had already been created, I couldn’t just go in and change the letter at this point. "Maybe I can just force it to look like an ‘o’," I thought. I tried layering various other sprites over it until finally, it looked like an ‘o’. Phew! - Akiman, Lead graphic design on SF2 (translated by Shmuplation) All about details Akiman description of the solution left me wanting more details. How did he turn an 'e' into an 'o'? Since I had a sheet extractor, I looked for the text and sure enough, the logo and the typo were found on sheet 0x7B00. The logo is drawn via 16 draw calls using tiles 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, and 0xDF. The w...