Attempt number 3... although somehow I feel it's gonna last less long than the first two.

I really enjoyed this one. Here is a quick overview of how I created the code:

• I started from the Brainfuck "Hello World!" on esolangs:

    ++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
  

  I had to modify it slightly to add the comma, but let's ignore the details...

• BF can be converted to ML fairly easily: change > and < to ) and ( respectively. Add a main floor beneath the program. Then implement loops via helper floors and elevators. That turns the above program into:

    ++++++++++>)+++++++)++++++++++)+++)+((((-[!)++.)+.+++++++..+++.)++.((+++++++++++++++.).+++.------.--------.)+.).
    =========="===============================#=====================================================================
              !                               <
              #==============================="
  

  This is a working "Hello World!" program in MarioLANG. (This code corresponds to the incorrect "Hello World!" on esolangs, not the obfuscated ML code above.)

• At this point, we can golf the code a bit my actually moving some of the loop code into the auxiliary floor. I'm now switching to the actual code from this answer:

    ++++++++++>)+++++++)++++++++++((-[!)++.)+.+++++++..+++.))]-.(----.((+++++++++++++++.).+++.------.--------.)+.
    =========="=======================#==========================================================================
              !((((-(.[)++++++)++++)))<
              #======================="
  

• And now the actual obfuscation: I figured the = would be a dead giveaway for Sp3000 who knew the language (he had used it in Evolution of OEIS). But MarioLANG also has "walls" instead of "floors", represented by |. These are functionally identical though, so I used the less common character. I also figured the hanging floor would look suspicious so I padded the two lines with other characters. For good measure I added the first line again to the end, and made the padding in the middle line the opposite characters of the first line. I also added matching square brackets (which are ignored by MarioLANG), because I figured an unmatched [ might be another strong hint. Finally, I wrote a CJam script to sprinkle exactly 13 = into random floor positions (13, because that's the length of Hello, World!) and changed the padding characters in the fourth row to Helo, Wrd! to make it look like I'm reading the characters from the source code, like a Befunge answer might. Voilà, obfuscated MarioLANG! :)

???, 549 bytes

++++++++++>)+++++++)++++++++++((-[!)++.)+.+++++++..+++.))]-.(----.((+++++++++++++++.).+++.------.--------.)+.
=|||||=|||"|||||=||||||=||||||||||#|||||||||=|||||||||||||||||||||||||||||||||||||||=|==|||||||||||||||||||||
----------!((((-(.[)++++++)++++)))<(--.(-.-------..---.((]+.)++++.))---------------.(.---.++++++.++++++++.(-.
Helo, Wrd!#||||||=|||||||||||||=||"||||||||||||||=||||||||||||||||||||=||||||||||||||||||||||||||||||||||=|||
++++++++++>)+++++++)++++++++++((-[!)++.)+.+++++++..+++.))]-.(----.((+++++++++++++++.).+++.------.--------.)+.

Attempt number 3... although somehow I feel it's gonna last less long than the first two.

MarioLANG, 549 bytes, cracked by Sp3000

++++++++++>)+++++++)++++++++++((-[!)++.)+.+++++++..+++.))]-.(----.((+++++++++++++++.).+++.------.--------.)+.
=|||||=|||"|||||=||||||=||||||||||#|||||||||=|||||||||||||||||||||||||||||||||||||||=|==|||||||||||||||||||||
----------!((((-(.[)++++++)++++)))<(--.(-.-------..---.((]+.)++++.))---------------.(.---.++++++.++++++++.(-.
Helo, Wrd!#||||||=|||||||||||||=||"||||||||||||||=||||||||||||||||||||=||||||||||||||||||||||||||||||||||=|||
++++++++++>)+++++++)++++++++++((-[!)++.)+.+++++++..+++.))]-.(----.((+++++++++++++++.).+++.------.--------.)+.

Attempt number 3... although somehow I feel it's gonna last less long than the first two.