The other day I came across the this blog post by Ron Gilbert called The Vertical Slice in which he rails against the creation of vertical slices. The following quote struck me:
"Vertical slices might work in a medium where you start at the beginning and grind though in a fairly linear fashion and what comes out is 90% complete. Maybe writing a novel works this way, but making movies and games do not. They are an iterative processes. You build foundations and the build up from there."
I love his image of the Mona Lisa's vertical slice. But Ron is using a different definition of vertical slice than I've always used. To me a vertical slice means is that we develop a feature to the point of knowing its value and use that knowledge to adjust the plan. The point being that the plan won't tell you how fun something is: the game will.
Ron's definition is that vertical slices emerge from a plan that defines all the slices up front. This might be a better approach from an engineering point of view over waterfall (fixing bugs along the way, etc), but it abandons the benefit of iterating on a plan with a working game. It doesn't surprise me that he's against that.
So maybe we should stop using this confusing phrase. Maybe we should call it a "game increment", or something. I'm open to suggestions.
By-the-way, here is how portraits were iterated on:
Also, da Vinci iterated on the Mona Lisa as well.