The Development Project is a HL2 modification made out of manipulated Dev textures as a project for those that enjoy the simplicity of the original measuring textures created by valve scattered throughout the map but also enjoy all the effects, adventures and creativity of regular mods.
Here I will take you for a run through of a few of the old maps for TDP back when it was first started as well as show you a couple concepts that were originally made.
Man you rock! :) keep going with that!