The Duke Nukem 3d Level Design Handbook (Duke Nukem Games)
Read this book when you're ready to build your own levels. Yes, it tells you how to use all the tools and effects , but more importantly, it shows you what makes a game level a grabber. Alongside the technical details are discussions of the artistic and strategic elements that hook players into your designs and glue them to their control pads. Pay attention to the tips from the retail game designers, Richard Bailey Gray (The Levelord) and Allen H.  Blum III. The 50 additional Duke Nukem 3D levels, editing tools and sample art on the enclosed CD are mighty handy, too.