The most important aspect in a Doom map, is of course, pumping your shotgun shells into hordes of monsters. Doom Builder makes this job easy with an intuitive interface and smooth controls.
Start by going to mode -> thing mode, or by pressing T on your keyboard. To insert an actor, either right click or press insert on your keyboard. You'll notice a popup window:
In the branching categories, the different things have been separated into their respective categories. By default, you'll be placing down a Player 1 start. Player 2-4 starts are for cooperative play, and the deathmatch starts are for, as you guessed it, deathmatch, FFA, and other modes. The things are colour coded according to the branch, so light green are player starts, salmon is monsters, blue is health etc etc. Doom Builder also automatically sorts everything by size when you place it, so you'll notice that spider masterminds have a bigger dot than imps or weapons.
Type is a DoomEdNum reference, or a unique identifier for any thing (you don't have to worry about this. Doom Builder automatically deals with this for you).
In settings, easy/medium/hard correspond to ITYTD, HMP, and UV. This is used to determine monster placement on different difficulties.
Deaf - Monsters do not "wake up" when they hear a sound. Instead they remain dormant wherever they are.
Multiplayer - Appears on gamemodes involving more than one player, so things like weapons or powerups for deathmatch
Not deathmatch/cooperative - Self-explanatory. Will not appear on these game modes.
In addition to the little image preview of our friendly green marine, there's an 8 button circle that tells you which angle the player will face. The angle number is available for a custom number that is not within a multiple of 45 degrees. In the image, our marine faces "down."
Let's go ahead and place some monsters, weapons, health, and decoration in our first room. You can view your thing placement using 3D mode (W). Here's what I ended up with. You grab a shotgun and shoot some imps, with some lamps in the corners.
Next, we're going to fill the rest of the map with monsters, but this time, we're going to try out the "deaf" flag. When we fight our imps, we don't want the whole hallway of monsters rushing towards us, so any monster we place in the hallway should be marked "deaf."
The cacodemons in this hallway can't hear us even though we're fighting so close because they're marked deaf.
Now you can go ahead and fill the rest of your rooms with monsters/weapons etc. Remember to watch out for ammo count! I ended the level with sort of a boss fight against a baron of hell in a slime pit.
At this point, you can test your map out by pressing the "play" button on the top toolbar, or by pressing F9 on your keyboard. If you jump into the slime pit, you'll see that you don't actually take damage. We'll discuss sector effects in the next section.
