How do you add custom textures custom midis or custom monsters to a vanilla compatible doom wad

in SLADE, look at the top toolbar for an option to set a base resource archive, and set it to doom2.wad (not doom 1).

then create P_START and P_END markers by creating new entries (using the top toolbar) and place all your individual desired textures (such as from the doom 1 texture pack) in between said markers.

next, select all your custom textures and right click them and go graphics->add to pnames. create a new import resource archive and select import from base. then reselect the textures and right click and do graphics->add to texturex. save your wad. all done c:

title - D_DM2TTL
intermission - D_DM2INT
endgame - D_READ_M

map01 - D_RUNNIN
map02 - D_STALKS
map03 - D_COUNTD
map04 - D_BETWEE
map05 - D_DOOM
map06 - D_THE_DA
map07 - D_SHAWN
map08 - D_DDTBLU
map09 - D_IN_CIT
map10 - D_DEAD
map11 - D_STLKS2
map12 - D_THEDA2
map13 - D_DOOM2
map14 - D_DDTBL2
map15 - D_RUNNI2
map16 - D_DEAD2
map17 - D_STLKS3
map18 - D_ROMERO
map19 - D_SHAWN2
map20 - D_MESSAG
map21 - D_COUNT2
map22 - D_DDTBL3
map23 - D_AMPIE
map24 - D_THEDA3
map25 - D_ADRIAN
map26 - D_MESSG2
map27 - D_ROMER2
map28 - D_TENSE
map29 - D_SHAWN3
map30 - D_OPENIN
map31 - D_EVIL
map32 - D_ULTIMA

To replace sprites, you can get away with instead changing the name of the sprite in whacked in the strings section. That way you only have to replace that one set of sprites instead of everything ||| Doomkid actually said this but I'm dull and thought he said the exact opposite. ||| (i.e. TROO [zombieman sprites] to CUST or something). You can find the strings for the sprite names at the bottom of the strings menu.

To create actual custom monsters/weapons, you'll have to use the states and things menus. The things menu (weapons/ammo menus for weapons) will let you change basic stats (hp, speed, etc.) and flags (gravity, shootable, etc.) on things as well as the starting states of each thing (spawn, attack, melee, resurrect, etc). The states menu on the other hand actually gives you access to each individual state/frame of every thing in the game. There you can rearrange frames, change their duration, and most importantly, change their action.

You're limited to the actions that exist in the game, so no additional projectile types or anything, and in vanilla in particular, you can only change the action of states that already have an action set. This is very very debilitating, as you cannot add actions to states that didn't already have an action in the first place. you can work to optimize and scrounge up some actions and states from various places if you need, such as removing some Chase actions (with serious negative repercussions). Please note that boom does not have this limitation. Also note that you cannot mix and match attack types: demons cannot use player attacks and players cannot use demon attacks, as I believe it has to do with targets, since demon attacks need targets that the player cannot give, and player attacks don't take targets into account which confuses the demons, both of which result in the game crashing. Also also note that you can have as many enemies as there are things, so if you absolutely need another enemy but already replaced Keens, Nazis, and whatever else, you can indeed resort to replacing a decoration or something instead, as long as you set their stats, flags, and starter states correctly. Also also also note, just because you might be interested in doing this for custom monsters, but you cannot change item drops. They're hardcoded. The thing occupying the zombieman's slot will ALWAYS drop a clip, things in the shotgunner slot always drop a shotgun, etc. So watch out for that and other hardcoded behaviors.

If you need a more in-depth tutorial on dehacked editing, I made a post a while back about editing the pistol, although much of what I explain can be applied to other aspects of thing-editing in dehacked: