Below you see two mockup images of the level for our time management game. The top image is a level I created for some technical tests. It gives an impression of the size of the level and there are some objects to click on. It was good enough to do some initial gameplay and technical tests (i.e. how fast the character should run, how complex the pathfinding should be, how this layout would work for the resolution we want to use).
After this, I started work on the next mockup level. We changed all layout stuff that didn't work that great. Note that the entrance has moved to the left lower corner of the screen, this works better with the widescreen resolution of 800 x 450 we're going to use. As you can see, we've also simplified the routes for the pathfinding. We've left some space in the top corners for interface elements. The animals and other objects have been scaled out of proportion to make them stick out better. Color, lighting and textures have been added to give a proper impression of depth, scale and speed. This is also done to test if all important elements will stand out once we start adding more 2D stuff. This level is good enough to work with while the programmers are adding in more functionality.
From this, we're now creating a proper model and texture plan to start finalizing the art for the background. Splitting the creation up in two or three steps helps determine level design problems early on, allows programmers to work with proper placeholders and prevents lots of fine art ending in the bin.