Vertical slice
Also said as Slice
A short part of the game finished to final quality in every discipline at once: art, sound, code, design and interface. It is one thin slice through the whole cake.
It proves that you can reach the quality you promised and tells you what a minute of the real game costs to make, so the rest can be estimated. It is also what publishers usually ask to see.
Say it
“For the funding milestone, build a ten-minute vertical slice: one level, final art and audio, one enemy type, one boss. Log the hours, because that is how we will budget the other eleven levels.”
Where you’ve seen it
A slice can also make a promise a game fails to keep. Aliens: Colonial Marines was shown at E3 in 2011 with a demo that looked far better than the game that shipped in 2013, and Sega and Gearbox were sued over the difference.
Not to be confused with horizontal slice
A horizontal slice covers the whole game at low quality, so you can check its length and flow. A vertical slice covers a sliver of it at full quality, so you can check it is good.