@Woolie Wool recently posted a few screens showing off his GZDoom settings in the Post Your Doom Picture (Part 2) thread and gave a few tips on how to make yours look that way.   Woolie's Settings: Basically what I'm doing is: Resolution scale: 640x400, actual resolution 3840x2160 @ 70 Hz cl_capfps 1 vid_vsync 1 NO anti-aliasing or texture filtering No mipmaps Distance fog: vanilla Software-style banding enabled Ambient occlusion set to maximum Tonemap setting: palette   It took me a bit to find and decipher some of these settings, as not all of them are clearly obvious where they are found in the menu, and some are misnamed from what they are in my version of GZDoom (3.6)   First, you will ask me, why not just use the software renderer?  Answer is simple, the software renderer doesn't render EVERYTHING in modern UDMF maps.  It is great for boom and vanilla and some UDMF stuff, but if a map uses a dynamic skybox or sloped 3d floors things will get weird... Anyway, I love how it looks, so I have decided to make a full tutorial on how to do this for yourself (and expand on it quite) a bit in GZDoom 3.6 (Some of these settings may not be available in earlier versions)   NOTICE: A lot of this is based on my personal taste, so if there is anything that you don't like...don't use it.  If something has (Important) next to it it is pretty necessary for it to resemble Software in any way.  I know my settings don't look EXACTLY like the Software Renderer, and it isn't even a "As close as it gets" kind of thing either.  But I think it looks good, if you don't, that's your preference :p   First off, let's load up gzdoom with whatever wad you like, and start a new game (or load a save, whatever, so long as you are in game) Go to SET VIDEO MODE and make sure RENDER MODE is set to OPENGL-ACCELERATED   We aren't worrying about resolution scale until the end of the tutorial, so ignore that for now.   Now, open the console with ~ then enter these commands:   cl_capfps 1 vid_vsync 1
Let's go deal with our textures now (and I suggest doing this whether or not you play with Fake Software Mode, unless you just like things blurry...weirdo)   In DISPLAY OPTIONS > OPENGL OPTIONS > TEXTURE OPTIONS use this setting:   TEXTURE FILTER MODE - NONE (LINEAR MIPMAP)
ANISOTROPIC FILTER - 16x (Suggested by @Gez to keep distant extreme angled textures from disappearing)   (Woolie's settings said "NO MIPMAPS" but LINEAR MIPMAP looks good to me with or without these settings.) The rest should be left at default.   Now let's head back to DISPLAY OPTIONS > OPENGL OPTIONS and make these changes if they aren't already set:   SECTOR LIGHT MODE - SOFTWARE
BANDED SW LIGHTMODE - ON (Important)
FOG MODE - STANDARED (Honestly I can't tell the difference between STANDARD and OFF, but RADIAL looks awful to me, and there is not one called VANILLA)
ENHANCED NIGHT VISION MODE - OFF
SMOOTH SPRITE EDGES - OFF
FUZZ STYLE - SOFTWARE
PARTICLE STYLE - SQUARE (Or OFF if you are a purist, but I like to see these effects) MULTISAMPLE - OFF
TONEMAP MODE - PALETTE (Important)
BLOOM EFFECT - ON (Another personal taste function, makes skies glow really nicely among other things)
AMBIENT OCCLUSION QUALITY - HIGH (Makes banded lighting pop a lot more in dark areas, maybe very necessary, maybe personal taste, depends on your eyes, I suppose)   Other settings can be left default.  Now your game should be looking pretty nice.  Let's do a few optional tweaks for those who want this to look more old school in DISPLAY:   SCREEN WIPE STYLE - MELT
USE FUZZ EFFECT - FUZZ
CLASSIC TRANSPARENCY - VANILLA (FORCED)
LOST SOULS TRANSLUCENCY - 1.00
ROCKET TRAILS - OFF
BLOOD TYPE - SPRITES
BULLET PUFF TYPE - SPRITES
NUMBER OF PARTICLES - I left mine default for my tastes, but purists might want to turn it all the way down
NUMBER OF DECALS - Same as above option
TELEPORTER ZOOM - OFF
MENU DIM - -0.00   Other settings can be left default.   In DISPLAY > DYNAMIC LIGHTS You may wish to switch DYNAMIC LIGHTS (OPENGL) to OFF, I have kept mine on because I think it looks freaking awesome!  But you do you.   Now in HUD OPTIONS you might turn DEFAULT CROSSHAIR to NONE to stay pure and in the SCALING OPTIONS submenu of HUD OPTIONS make these changes if not already set:   USER INTERFACE SCALE - ADAPT TO SCREEN SIZE MESSAGES - 5
STATUS BAR - 8 
FULLSCREEN HUD - 8
ALTERNATIVE HUD - 8 HUD PRESERVES ASPECT RATON - ON   Now you are mostly good, but resolution scale will really set it off and sell it.  And I know everyone uses their own resolutions and aspect ratios so set your real resolution however you like, we are going to downscale it to a more classic looking style.   Now, go to SET VIDEO MODE and use these settings:   FORCE ASPECT RATIO - OFF
RESOLUTION SCALE - CUSTOM Click APPLY CHANGES (WINDOWED) if you play in a window. APPLY CHANGES (FULLSCREEN) for fullscreen.   Now exit the menus back to the game and open the console once again and use this command:   vid_setscale <width> <height>   This will put the game into whatever low resolution you want without resizing the window (and if you use fullscreen i assume this will keep your system from forcing the resolution you use on other monitors, but I don't use fullscreen because it acts fucky on my system)   I play in a window that is 1792x1008 and I use a resolution scale of 1066x600 so my command would be:   vid_setscale 1066 600   It looks nice and chunky, I like it, you may want a different resolution and aspect ratio, just play around with it until you find one you like, and don't be afraid to use an online aspect ratio calculator if you need to (I did, lol).   ONE FINAL STEP: MAKE A SAVE GAME!  This is important, I cannot stress this enough (and I'm not sure why I forgot to add this originally, it is the whole reason we started this from in-game) GZDoom likes to forget settings if you don't save, I'm no expert, but my theory is that it saves your ini file at the same time it makes a save game.  So make a save and name it like TEST or something, you don't need to ever load this save for settings to be retained though.  I would always make this a habit in GZDoom, if you change any settings, make a game save.   This tutorial wouldn't be possible without the help of some really cool people from here on Doomworld who gave me tips in this endeavor to getting my game looking cool, how I like it:   @Woolie Wool who originally posted the brief settings on the picture thread.
@Redxone who gave me the vid_setscale console command I despeately needed to top it all off.
@Gez who gave me some settings for the actual software renderer back before I started working on this. @Tango who suggested using Bloom.  Big thanks there.   And enjoy a few screens posted in the first comment block.  (The screenshot function will output an image the same size as the fake resolution you are using, so I am scaling the images up to 1080p in photoshop)   EDIT: A new 3.7 version of GZDoom has released with a new "Vanilla" sector light mode.  I won't be able to test out how this looks for a while since I'm at work, but you might try it out and see how it looks with these settings.