What is the secret of Monkey Island?

The title of the first game in the series was "The Secret of Monkey Island". What is the secret?

I remember when playing each Monkey Island on release (with the exception of the Tales of Monkey Island) - and in each of the first 4 games I always remembered "knowing the secret of Monkey Island".

During the end of the first game I assumed it was the fact the undead LeChuck was hiding with the catacombs of a giant monkey head. I didn't think there was anything to suggest the secret was anything more complex or yet unexplained after finishing the first game. The game had an ending and there was nothing to suggest the story would continue after the demise of LeChuck.

When I played the second game, I had no doubts about my conclusions for the first game until the end when LeChuck reveals himself as your brother (and everything in the two games was a fabrication). I remember still thinking that the secret was the way LeChuck was hiding on the island - but because now everything before wasn't real it didn't matter what the secret was. When talking to others after playing the second game some believed the real secret was actually Big Whoop (although I didn't come to the same conclusion).

The Curse of Monkey Island made an arguably weak explanation of events between the second game and the start of the third game. However, everything previous was thrown out when Guybrush asks LeChuck for the secret of Monkey Island - as if the secret was in fact never explained before.

The fourth game is explicit in that the monkey kombat is the real secret.

Remember, by the time the first three games were released the internet was not like we know it today. It seems to me that the on-going notion of the secret never being explained has become a running joke fuelled by online debates, when in fact there was no problem during the first 2 games.

Conclusion

The secret was the fact an undead LeChuck was hiding under the monkey head (implied).

This then changed during the series to the fact the giant monkey head was part of a robot (explicit).

The asking of "what is the secret of Monkey Island" became a running joke perhaps from the third game, and continues beyond the fourth game (despite the explicit revelation).

The secret of Monkey Island seems to be massive Voodoo powers, including Eternal Life. Or rather, Eternal Death.

• Secret of Monkey Island - LeChuck went to find the secret and came back as a ghost.
• LeChuck's Revenge - LeChuck was resurrected by Largo LeGrande using an offscreen Voodoo ritual of some sort. LeChuck clearly has Voodoo powers during the game. At the end of the game, it's implied that he has locked Guybrush into some sort of hallucination or just outright cursed.

Unfortunately, being the only two games Ron Gilbert was involved with meant that the story started to veer off course a bit:

• When Jonathan Ackley and Larry Ahern wrote Curse of Monkey Island, they kept the Eternal Death theme going, but dropped the Voodoo powers bit. They also added a giant carnival to try to explain the ending of LeChuck's Revenge
• Escape From Monkey Island outright ignored canon and made the secret the giant Monkey Robot below the island (which was clearly not there in the first game)

Tales From Monkey Island went back to the "LeChuck has Voodoo Powers" bit. This shouldn't be a surprise as Ron Gilbert was involved in the production of this game.

One key point late in the game was that LeChuck existed in both the world of the living and world of the dead at the same time.

It was also implied that LeChuck's power (the secret of Monkey Island from the first game) can be transferred to other people. This started with The Pox of LeChuck and the after-credits scene at the end of Tales.