Trent Kanuiga is quite a popular concept artist that has been involved in many video games in the past, e.g. world of warcraft, League of legends etc. In one of his youtube videos he discussed the usage of concept artists using grey boxes, grey box is pre-alpha build of a games environment, the grey box essentially id for level design trying to create the level, the grey boxes are levels that look grey typically they have grey shapes around the environment, concept artists use the grey boxes to make artwork sketches plus it's useful when it comes to photo bashing. Here is how I did it.

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First I created a mood board consider how well the last one was I made another mood board that better captures the mood of the game.