So i was watching TobyGames for a long time, and he is apparently using 1.2.5 for his Aether lets play. I honestly prefer the original aether mod over Aether II. But when i look in the bin folder in my .minecraft folder, the "minecraft.jar" file is not there. Has it been moved to "versions?" I Know that i have to move all the mod contents into the minecraft.jar file using 7zip, but i just cant find the damn file. It is possible i need the original old launcher, and if thats the case, could someone please link me to its download? If someone out there could help me i would be so thankful. I await any response.
There is a way to go about it but I'd say go with MultIMC and install Forge 1.2.5 to it (Forge is easy to put on it but Risugami's Modloader isn't so easy with a install button, if Aether 1 does require it that is). There is a few in the community that have gotten old versions to work on it so I'd look to some their Discords or Youtubers that have done this like ScottoMotto.
I can't sadly link to Modification Station as the invite I got was temporary... I'd ask around if you can get to them/find an invite.
Otherwise as I'm unfamiliar with older versions I myself use modpacks that were made in the last 3 years that are for 1.2.5 like the Industrial Aether modpack and play what mods are in those (a Technic modpack). I'd say look to things like those if you don't want the hassle of MultiMC META-INF/old modding ways to deal with or just get mods from a modpack like the one I suggested and pick whichever from it and see what requirements they need. I think Aether 1 doesn't need too much to get working though.