2 = Inverse Square (More akin to real-world light calculation)
Dot product weight (dot_product_weight) -
Spherical Ambient (spherical_ambient) -
Angle Hotspot (angle_hotspot) -
Falloff curvature (falloff_curvature) -
Angle Penumbra (angle_penumbra) -
Falloff Start Distance (falloff_start_dist) -
Falloff End Distance (falloff_end_dist) -
Initially dark (1) - If this is enabled, the entity will need to be triggered to work.
The Custom Appearance (pattern) property allows you to enter a string of letters from a to z, representing brightness. If you entered 'abcdefghihgfedcba' then the light would go from bright to dim and back again and then repeat. To use this feature, you must name the light. However, if you then use a trigger to activate it, then it will behave as a normal light without a custom pattern.
You can't have more than 4 named lights in the same visual area - because the compiler will have a difficult time allocating separate lightmap data for each light that can be turned on and off.
Glitch: Somehow, the engine (or rad compiler?) opts not to draw the light reflections/bright on the surface of nearby entities (anything 3D other than a brush) when there are SKY textured walls around the light entity. See an example here.
Solution: Create a relatively large block anywhere between the light entity and the sky (usually, er, above the light entity); the "shadow" of this block will delimite where the glitch should be fixed. Apply SKIP texture on all of its faces and a black_HIDDEN on the face parallel to the light entity (usually bottom/top).