here you will find tutorials for everything:
how to make minecraft 1.21.1 look like 1.2.5?
requirements:
minecraft 1.21.1 (duh)
fabric loader as well as fabric api
Architectury mod
*nostalgic tweaks
*you need nostalgic tweaks for this to work!
first step is to download all mods (you can use mutliMC / prism launcher / other forks)
For Fabric loader and fabric api
note: you should be able to download all of those mods from the mods category in prism launcher / multimc
also you should know how to install mods in Minecraft? right?
make sure after installing nostalgic tweaks to press O and then into manage button and go to "import & Export" and before clicking on client import: Download this! then you can click on Client import and it should say it was successful
now for texture packs:
for modern Minecraft textures that normally programmer art doesn't cover i recommand: programer art continuation project
as well as c418 Music only for only c418 music and not moden minecraft "music" bullshit... also make sure to press O (for old in Nostalgic tweaks) go to config menu and search for word "music"
and make sure that those two options are set to "blended"
and also make sure to get Vanilla Tweaks but only thing named:
"No Java Edition Subtitle" in gui tab.
you don't need anything else (but you can check other things too who cares im not stopping you!)
put all texture packs to resourcepacks folder in your MC game folder
and now select texture packs like so
-C418 Music only
-Vanilla Tweaks
-PACP_Base_Release
-programmer art
-fabric mods
-default
done. have fun.