/vr/ - Retro Games

I want to fight Akuma in Super Turbo, but I don't understand the methods because everywhere I look gives me a different answer. Some say you have to make it to M. Bison on a single credit. Some say you can use more credits, but if you do, you have to make it to him in less than 20 minutes (I've also read 25 minutes). Other sources say you need to get a "high score" (but they never specify what score you need to reach). Some add that you need to score three perfect rounds.
Can someone give me a straight answer on this? What are the ACTUAL methods? I would just hate to take the easiest option possible only to find that he doesn't show up and that I've been wasting my time. And for such a classic game, it's weird to me how arcane this information seems to be.

not only is he unlockeable and badass but hes a fucking secret