Around 1 hour 29 minutes to beat. The SNES version took a little over an hour but the final boss in this one was definately harder. With the final boss I had to not lose any lives during the enemy portion of the final stage so that I could survive with 1 life remaining. Multiple times I killed the boss as I lost my final life and it didnt count. The pattern seems to change later in the fight and becomes very hard to dodge.
Only edited out deaths on the final stage since progress moved pretty fast through the rest of the game, and there wasn't always clear checkpoints. Check out the tutorial version for a complete breakdown.
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