Prism Launcher is a lightweight, third party mod launcher and instance manager for Minecraft. It's a fork of polymc which was a fork of MultiMC.
It is recent, as in, 2 days old, yet it already has a massive following due to the fallout of the previous project. The founder of PolyMC banned the entire dev team and went on a far right tirade in the PolyMC server. Prism is the fork made by the devs to regain control of their work.
Existing ebuilds (gentoo prs) https://github.com/gentoo/gentoo/pull/27860