Ninja Theory's take on testing a game.
Tameem Antoniades says :
'As you may know we are currently working on our Vertical Slice, the details of which were covered recently here
In summation, it is a small section of the game to near-finished standard that allows us to see if the game we imagined in our heads actually works! The vertical slice covers everything from combat, exploration, puzzles, visuals, audio, music…the full shebang.'