Release

[!] READ THIS

For some reason the official legacy runtime for the Minecraft launcher does not support download from any urls. To get around this I suggest using a different java 8 runtime to launch this in the official Minecraft launcher.

[?] What is this? What do I do with this?

Drop these files in a folder called Sigma5 in your .minecraft/versions folder and press Play in the launcher on the version that says Sigma5.