Guides (Sorted by Engine)

Engine-Agnostic ("Quake-Based")

Accelerating Map Compiles in Quake-Based Engines (February 18, 2018) Optimization and smart decision making can drastically reduce your compile times.

Config Files, and How to Make One (October 7, 2017) Config files are lists of commands that can be run in-game. Writing your own can save you time when running commands.

r_speeds and Optimizing Quake and GoldSrc Levels (September 22, 2017) Well-optimized levels separate the classics from the abandoned slideshows. Keeping an eye on your r_speeds when working with Quake and GoldSrc levels is an absolute necessity.

Source General

A Primer on Tool Textures (September 13, 2017) Tool textures are special, unseen textures that play an important part of mapmaking when it comes to scripting, visibility control, and map optimization.

Constant, Linear, and Quadratic Lighting in Hammer Explained (September 26, 2017) Hammer includes three cryptic keyvalues that completely change the way your lights render in-game: constant, linear, and quadratic attenuation.

Controlling Visibility with Areaportals and Occluders (September 30, 2017) There are times when your map renders more than it should and VVIS can't help. Special brush entities may be able to squeeze more juice out of your map in busy areas.

Cubemaps: What They Do, and How to Use Them (October 10, 2017) Cubemaps are an important part of getting shiny materials to shine. Each game has their own caveats to getting them to render and work properly, however.

Custom 2D Skyboxes and the light_environment Entity (December 7, 2017) A custom 2D skybox texture adds a layer of polish and ambience to a map, and a well-configured light_environment can enhance the effect.

Entity Interactions in Source's Input/Output System (February 11, 2018) Source's I/O system replaces the old target system for entity interactions. Here's how it all works.

Getting Around in the Material System (January 31, 2018) In the Source engine, materials, sets of images and text files, replace the traditional way of storing and rendering textures.

Making Use of Source's Water Materials (December 3, 2017) Water in the Source engine is more complicated than you might expect.

Nodegraphs: The Key to Intelligent NPCs (September 27, 2017) AI nodegraphs are an integral part of level scripting and design, and having a good one means challenging enemies and helpful allies. Fortunately, they're easy to create.

Prop Types in the Source Engine (October 3, 2017) The Source engine uses 3D models called props to populate its levels. Not all prop entities work the same, however, and there's many different types.

The Showbudget Panel and Optimizing Source Levels (October 1, 2017) A well-optimized map means happy players. You can make use of a little-known debug feature in the Source engine to determine exactly what's slowing your map down.

Understanding Source's Physics Constraints (January 22, 2018) Source's physics engine can simulate a variety of constraints, or ways objects are attached to one another.

What Goes Into Compiling a Source Map? (November 16, 2017) Maps need to be compiled before they can be played in-game. This guide attempts to explain in-depth what each tool in the process does.

Quake

Colored Lighting in the Quake Engine (December 20, 2017) Quake, through custom compilers, supports colored lighting. Here's how to get it working.

Features of Modern Quake Source Ports (May 24, 2018) Modern-day Quake source ports add a variety of new and enhanced features for level designers to make use of, such as fog, colored lights, or texture transparency.

Investigating the "Wider is Better" VIS Anomaly (April 22, 2018) An old article claims that thicker brushes lead to shorter compile times. The Valve Developer Union investigates.

Item Spawns in Custom Quake Levels (November 2, 2017) The way you, as the level designer, place items in a Quake level can affect the look, difficulty, and flow of the entire map.

Quake Entity Guide: Weapons and Items (Unreleased, slated for January 28, 2018) A reference listing of Quake's weapons and items.

The VDU Starter Kit for Quake and Hexen II Modding (Unreleased, slated for May 27, 2018) So many tools, but which to use? This guide contains recommendations for Quake and Hexen II mappers just starting out.

Ten Things I Learned Building a Quake Level in 2017 (November 19, 2017) pac, the main writer for VDU, lists off a set of mapping tips and guidelines he learned while working on "Temple of the Strange", his first Quake level.

Half-Life

Deathmatch Deconstructed: Bounce (June 19, 2018) Following Stalkyard, VDU expands upon the successes and failures of HLDM's Bounce.

Deathmatch Deconstructed: Stalkyard (February 25, 2018) The first in a series on dissecting HLDM maps, Stalkyard's strengths and weaknesses are examined in-depth.

How They Did It: Special Effects in Half-Life (April 8, 2018, by Windawz) At its release, Half-Life's effects and scripted sequences were ingenious and revolutionary. In this guide, we break down the entities and effects that make it all tick.

Power Up: More Special Effects in Half-Life (May 13, 2018, by Windawz) More of the scripted sequences and effects in the original Half-Life are dissected and examined.

Properly Avoiding the "Pollen Sprites" in Half-Life (November 12, 2017) NPCs in Half-Life placed around tight, complex geometry will give off yellow error sprites that look like pollen. You can use a scripted_sequence entity to fix this.

Minecraft

Understanding Light Level Mechanics in Minecraft (April 1, 2018) Getting ambushed? Can't get anything to grow? It could be your light levels that need adjusting.

Ricochet

Anatomy of a Ricochet Level (October 6, 2017) Ricochet's gameplay has players hopping between platforms and launching discs at one another. This analysis deconstructs a Ricochet level to determine how it all works.