https://opengameart.org/content/astrounaut-walking

https://www.spriters-resource.com/pc_computer/strife/

Textures

https://opengameart.org/art-search-advanced?keys=Golgotha

Weapons

• Punch dagger

https://github.com/freedoom/attic/tree/master/wildweasel/fist

Leave as is or add in a dagger or knuckleduster. Maybe Wolverine style claws?

The punch in this first verison might be worth looking into:

https://github.com/freedoom/historic/blob/trunk/pre-0.1/2002-02-21.wad

• Crossbow

https://github.com/Blasphemer/blasphemer/blob/master/sprites/crbwa0.gif

Edit it to fire blue electrical arrows and the poision darts.

Animate this and submit it to Blasphemer to free the old crossbow up:

https://www.doomworld.com/forum/post/2064572

• Assault rifle

https://github.com/freedoom/attic/blob/master/fredrik/oldshotgun/

Edit the cocking to work as the at rest sprite.

• Mini-missile launcher

https://github.com/freedoom/attic/tree/master/fredrik/rocketlauncher

The one from this version might be better, but it is not in the attic for some reason:

https://github.com/freedoom/historic/tree/trunk/0.3

And a possible pickup sprite:

https://github.com/freedoom/attic/tree/master/z86/sprites

• Grenade launcher

https://github.com/freedoom/attic/blob/master/fredrik/plasma/

• Flamethrower

https://github.com/freedoom/attic/tree/master/railgunner/bfg

• Mauler

https://github.com/freedoom/attic/tree/master/fredrik/skag

• Sigil

https://github.com/CireG/Zauberer/blob/master/sprites/561qq65_by_raymooh...

Will need to be edited around for the four stages. The bulbs on the side and the barrel would work.

Probally a good idea to give back to Zauberer if this got used.

Or maybe...

https://opengameart.org/content/nimrod-scrittls-spaceships

There is also a rather interesting BFG sprite in this pre-alpha version of Freedoom.

https://github.com/freedoom/historic/blob/trunk/pre-0.1/2002-02-21.wad

Beings

3D models are to be rigged, posed, captured and touched up into sprites.

Static sprites are to be edited or redrawn into five/eight directions. Some possible shortcuts are outlined here:

https://opengameart.org/forumtopic/how-to-make-all-options-for-an-8-dire...

The original Doomworld thread had proposed a steampunk look with clockwork automata, which would not be a bad idea to aspire to.

•  Turret

https://opengameart.org/content/sci-fi-turret

• Acolyte

https://opengameart.org/content/purple-sci-fi-soldier-fps-sprite-sheet

• Templar

https://opengameart.org/content/low-poly-robot-golem-with-hand-painted-t...

• Crusader

https://opengameart.org/content/exotrooper-low-poly

• Reaver

https://opengameart.org/content/mech-character-model

• Inquisitor

https://opengameart.org/content/winged-mecha-model-and-iso-sprites

• Sentinal

https://opengameart.org/content/futuristic-drone-in-3d
https://opengameart.org/content/ufo-spritesheet-0
https://opengameart.org/content/phantasy-tiny-rpg-mobs-pack-2

• Stalker

https://opengameart.org/content/low-poly-bug-robot
https://opengameart.org/content/phantasy-tiny-rpg-mobs-pack-2

• Peasant

https://opengameart.org/content/mudeater-animated

• Beggar

https://opengameart.org/content/monk
https://opengameart.org/content/green-assassin

• Rat

https://opengameart.org/content/rat-0

• Rebel

https://opengameart.org/content/human-guard-for-sprite-based-fps

• Merchant

https://opengameart.org/content/modular-rpg-characters

• Macil

https://opengameart.org/content/monster-mutant-leader-for-fps-game

• Bishop

https://opengameart.org/content/low-poly-robot

• Oracle

https://opengameart.org/sites/default/files/gnom.png

https://opengameart.org/content/surts-cc0-scraps-transparent

• Spectre

https://opengameart.org/sites/default/files/flota.png

https://opengameart.org/content/surts-cc0-scraps-transparent

• Loremaster

https://opengameart.org/content/evil-cyborg

• Programmer

https://opengameart.org/content/rotund-space-ship

https://www.doomworld.com/forum/post/1423003 (far left)

• Entity Egg

https://opengameart.org/content/egg-blast

• Entity

https://opengameart.org/sites/default/files/deem.png

https://opengameart.org/content/surts-cc0-scraps-transparent

• Portraits

https://opengameart.org/content/cyberpunk-portraits

https://opengameart.org/content/rpg-characters-avatars

Objects

• Barrel

https://opengameart.org/content/barrel-0

https://opengameart.org/content/50-gallon-drum

Loose

https://www.doomworld.com/forum/topic/89075-group-effort-to-find-lost-as...
https://www.geocities.ws/catodemos/freedoom/
https://github.com/Blasphemer/blasphemer/blob/master/sprites/crbwa0.gif
https://github.com/freedoom/attic/tree/master/cheapalert
https://github.com/freedoom/attic/tree/master/espi/pistol
https://github.com/freedoom/attic/tree/master/fredrik/minigun
https://github.com/freedoom/attic/tree/master/fredrik/all_green_shotgun
https://github.com/freedoom/attic/tree/master/fredrik/plainsaw
https://github.com/freedoom/attic/tree/master/fredrik/ssg
https://github.com/freedoom/attic/tree/master/chang/ruby_plasma_rifle
https://github.com/freedoom/attic/tree/master/railgunner/chaingun
https://github.com/freedoom/attic/tree/master/ebola/chaingun
https://github.com/freedoom/attic/tree/master/ebola/shotgun
https://github.com/freedoom/attic/tree/master/mellow/shotgun
https://github.com/freedoom/attic/tree/master/scubasteve
https://github.com/freedoom/attic/tree/master/saint_of_killers
https://www.doomworld.com/forum/topic/98804-half-baked-super-shotgun-spr...
https://www.doomworld.com/forum/topic/3691-skag1337/
https://www.doomworld.com/forum/topic/4482-something/
https://www.doomworld.com/forum/topic/4696-heavy-weapon-dude/
https://www.doomworld.com/forum/post/323186
https://www.doomworld.com/forum/topic/54925-sodaholics-new-chainsaw/
https://www.doomworld.com/forum/topic/69106-concept-sprite-for-a-lever-a...
https://www.doomworld.com/forum/topic/69129-wolf-ss/
https://www.doomworld.com/forum/topic/86075-how-about-making-weapons-mor...
https://www.doomworld.com/forum/topic/105583-two-small-sprites/
https://www.doomworld.com/forum/topic/111845-i-did-the-new-texture-for-t...
https://www.doomworld.com/forum/topic/74600-weapon-graphics-discussion/
http://web.archive.org/web/20150918104121/http://www.doomworld.com/vb/fr...

Honorary Mentions

Good, but the license does not fit:

https://opengameart.org/content/kraken-mech-justin-nichols-concept
https://opengameart.org/content/demon-alien-character
https://opengameart.org/content/android-mki
https://opengameart.org/content/hextraction-base-player-pod
https://opengameart.org/content/robopk20
https://opengameart.org/content/low-poly-hooded-character-rigged-blender
https://opengameart.org/content/spider-spy-drone
https://opengameart.org/content/spider-spy-drone-0
https://opengameart.org/content/sap-1-sapper-bot-mark-1
https://opengameart.org/content/brain-robot
https://opengameart.org/content/smallrobo
https://opengameart.org/content/ahz-27
https://opengameart.org/content/octobot
https://opengameart.org/content/robot-5
https://opengameart.org/content/giant-robot
https://opengameart.org/content/uskir
https://opengameart.org/content/cyborg-wheeler
https://opengameart.org/content/bullfrog-support-mech-mode
https://opengameart.org/content/mechs-64x64
https://opengameart.org/content/lichl
https://opengameart.org/content/heavy-turret
https://opengameart.org/content/sensorradar-tower
https://opengameart.org/content/four-science-fiction-buildings
https://opengameart.org/content/sci-fi-tileset-layer-computers-and-equip...
https://opengameart.org/content/11-portraits-108px
https://opengameart.org/content/5-portraits-108px
https://opengameart.org/content/9-portaits-108px
https://opengameart.org/content/oracle-portrait
https://opengameart.org/content/portraits-for-naev
https://opengameart.org/content/vegastrike-portraits
https://opengameart.org/content/60-terrible-character-portraits
https://opengameart.org/content/paperdoll-male-character

Any chance you would consider making a male and female base in the style of this?

Technically I didn't even rework it, just dug it out of the Wayback Machine.