Just started the game & I can't move I'm just staying in that desert on spot. If that's the intro it's sure the long one.

Apparently, you got to press left to move right.

Press the right arrow :)

I did that, it failed because I made adjustments to controls.

This intro (not that long) simply consist in walking to the right in this desert until... you'll find out very soon (and then the game will begin).

(this intro is very similar in GRIS)