Mortal Kombat 9 (2011): How to Get Hide and Seek Achievement/Trophy
In Mortal Kombat (aka Mortal Kombat 9, 2011 version) for the PS3 and Xbox 360, you can fight Classic Smoke in Arcade mode to receive the hidden Hide and Seek Achievement/Trophy.
On The Living Forest stage, wait for Smoke to peak out from behind one of the trees, and immediately press Down plus the Back button on Xbox 360, or Select on PS3. Do this repeatedly and quickly, and Classic Smoke will come out to fight you.
Check out my other guide if you’re looking for the other Hidden Kombatants for achievements or trophies.