Building 3D scenes for games can be a difficult task, especially for beginners and other non-experts wanting to contribute their own ideas in an easy way. Tools for map or world creation are often complex to understand and use, don't support the creative process of building a scene, and decouple design from player experience. To overcome these problems, we present a First-Person Shooter (FPS) game for level creation using game mechanics for all tasks, making the process more easy and enjoyable while also providing direct experience of the work from a player's point of view. We evaluated our approach in a preliminary study where we compared our game to a simplified version of the Unity editor, representing generic world building tools, and found that users enjoy the our game, find it more usable, and feel more creative.