Greenlight gates and vertical slice

As we already know, game development is risky and expensive. To minimize the risk, during the life cycle of a project it will likely have to go through at least one greenlight gate—a point at which the fate of the game is being decided. A failure to greenlight will force the team to go back and iterate on the idea or result in the game being canceled altogether.

Before real production starts, game designers work with their producers to create and present the initial greenlight documentation to the key stakeholders in the company, hoping to convince them that the concept being proposed is a wise investment of time and money.

Once development starts, a version of the game itself is what's being shown. It's a common practice to start the project with the aim of spending the first several months on creating a so-called Vertical Slice. Vertical Slices are essentially demo versions of the main game hoping to showcase its potential, prove the artistic vision, and validate basic gameplay mechanics. Think of them as vertical slices of a cake: it may cover a very small area of the final product but contains all major ingredients (game systems are essentially horizontal layers). It serves as a good indication of whether it's worth the commitment to make the whole cake/game.

It's not uncommon to use Vertical Slices to present the game to the press, create teaser trailers, as well as to try and get external investors or publishers on board with funding the project. However, at diligent studios, many games will get canceled before they get that far.