A level designer is a game designer who creates environments and scenarios using a level editor and other tools.
Level designer will usually work on a level from pre-production to completion; working with both incomplete and complete versions of the game.
Game programmers usually produce level editors and design tools for the designers to use. This eliminates the need for designers to access or modify game code. As opposed to the level editing tools sometimes available to the community, level designers often work with placeholders and prototypes aiming for level consistency and clear layout before required artwork is produced by game artists.
Many level designers have skills as both a visual artist and game designers, although in recent years the responsibility for visual, structural and gameplay related tasks has been increasingly divided among several specialists.
A level designer may also be called a mapper; this term is used in reference to people working on lower level free mods. This term applies to people proficient in specific areas of the level design process, such as creating geometry while not properly illuminating it. The term "level designer" describes someone who has attained full knowledge of the engine they are designing for, so that they may control all aspects of the player experience.
In addition to making the environments the player inhabits in the game, a level designer may also work on enemy or non-player character placement and scripted story-line events. They may also write high-level code, altering game rules or scoring.
(source: wikipedia.com)
