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.
A simple picture of hammer with the kill_counter and everything else on my desktop.
The lux_kill_counter is able to count each npc death triggered in-game then sent to hammer allowing the mapper to have a more accurate kill count and use it for triggering various this such as rooms with weapons or just to simply display the kill count like here.