This is a list of how to get the Key on each world. The Key is an item that you can collect, which will appear after a particular condition is met. You need to collect the first 9 keys in order to unlock the final world in order to get the good ending. There is a key on the final world, but that is just to unlock a battle game stage and is not needed for the good ending.

The key for each world is found on the 5th level of each world. Unless it is hidden in a soft block, the key will appear in a random spot on the stage once the requirement is met.

World 1: Hidden in a soft block World 2: Defeat all enemies World 3: Appears after you are in the stage for 2 minutes (when the timer hits 1:00) World 4: Destroy all soft blocks World 5: Defeat all enemies & destroy all soft blocks World 6: Defeat all enemies World 7: Get stunned by one of the electric floor traps World 8: Get an enemy crushed by a press tool trap World 9: Bomb the exit

World 10: Hidden in a soft block (Not needed for speedrun, but noting for completion sake)

NOTE: I learned you CAN get Keys on other stages (probably only certain stages), but I don't know the exact requirements. I had a Key pop up for me on 6-9 but I am unsure what made it pop up. (I didn't see it pop up as it appeared off screen; I had taken out all the enemies and took out all the soft blocks except for 1, which had the teleporter in it) I have to assume you can get a key on the 9th stage of every world but I can't be sure (nor do I know the requirements to test but if anyone wants to look into it, I'd be curious on the information).