In your Launcher (Official or MultiMC), edit the Alpha installation and add these JVM arguments to force the old renderer:
-Djava.library.path=natives -Dforge.forceNoStencil=true
Many users search for a direct download LINK because the official launcher sometimes hides historical versions. If you don't see "old_alpha a1.2.6": Minecraft 1.2.6 Alpha Download LINK
Solution A: Enable Historical Versions
Solution B: The MultiMC Workaround If the official launcher crashes on your modern PC (common with Alpha), download MultiMC (an open-source launcher). It handles old Java arguments better. In your Launcher (Official or MultiMC), edit the
You must have purchased Minecraft Java Edition at any point in the past. If you have a Microsoft or Mojang account, you are eligible. Solution B: The MultiMC Workaround If the official
Go to the official Minecraft website and download the standard Minecraft Launcher for Windows/Mac/Linux. (This is the universal link).