I haven't tried it yet, but the code Sektor mentions is K-O-N-N-1-H-5. Probably does nothing, but I hope that helps.

The code can only be button commands not numbers or letters.

in the MK DECEption Strat Guid there is number codes all threw the boookkkk
i forget wat they were for. But some one should definetly try those on that question mark. the numbers of the codes are converted to buttons.

Or more specifically, the right hallway in the MKDA main screen setup.

maybe shinnok says the kode or hints towards one.

Just a thought, the code can use any of the 12 buttons, so K-O-N-N-1-H-5 could mean start, kick, throw, down, down down, , x button, high punch, block

I know if it was in the game it was probably taken out long ago, but maybe you can unlock "The Portal" arena, as I remember seeing a screenshot of it in Armageddon with a KAK and Sub-Zero in his alternate fighting.

I bet many people have tried it but just in case....anyone try the DULLARD code?

The code is only 6 characters long, but i tried the dullard code without the a, or something equivalent.

I tried XXXXXX it didn't work and the start button can't be pressed to enter the kode

I tried x,x,x,x,x,x nothing happens and start isn't available to be pushed to enter the kode

Okay this is what I think.
The pictures at the main menu there are six of them, right?
Well after closely looking at those pictures I've noticed there are buttons hidden in them (well I assume there are). Anyway. this is what I have
X - Kitana and Mileena picture the statues are holding a blue circle (the x button's color)
left - Sonya and Kano picture the sign behind Sonya with the arrow pointing to the left.
R2 - Scorpion and Sub-Zero picture there is a desing at the bottom of the moon that looks like R2 to me.
down - Johnny Cage and Goro picture if you look closely at the topJohnny Cage's hair you see a faint down arrow.
Square - Liu Kang and Shang Tsung picture on the ground behind Liu Kang there is a pattern, (easier to see it when the lighting strikes)
L1 - there is one more picture left but it's slipped my mind right now.
but if this is right, all I have to do is put them in the right order. And boom I have it, maybe.

GENIUS, you narrowed the number of kodes from 3000000 to 36 GENIUS

I was just playing the game in Reiko's War Room. Perhaps the writings on the floor reveal something. There are items that look like Triangles and circles. I suck at finding out codes but its definitely worth a look