The three virtues of a programmer: Laziness, Impatience, and Hubris. – Larry Wall
In this, the first of many parts, I will explain how to make a very simple door that opens when you bump it
First, set up your doorframe with a room on either side (usually doors do lead to somewhere). Texture it and light it, whatever you need to do to make your level to your liking. Then make the door. The door we are going to make is just a mover that is more vertical than horizontal, and spans the area between two walls to block it. Doors can be made any shape, size, or made to go in any direction.
To make the door, build a mover with the nessecary door textures applied that is large enough to span your doorfame, and place it in your doorway. (see Create A Mover for more on this step).
Right click on it and alter the keyframe 1 to the position you want it to be after the door is opened. This can be up, down, left, right, or rotated in any way from the base keframe. All you have to do is tell the door where to be, and the engine will figure out the rest. The required properties of our door are now in place, and all that is left are the sounds that it gives off when moving.
Unless you want silent doors, you will have to attach sounds to your door. To do this, right click on the door and select Properties (is it F8 that does the same thing?). Expand Mover Sounds. You will see a list of tags. These are the different times a door can emit a noise.
To be finished at a later date (5/14) or by a different person at a sooner date. –WheatPuppet
I have to wonder if there is anyone who really needs this tutorial, or if I am doing this out of a sense of completion... It's all good though