Melee

Super Smash Bros. Melee is a 2001 platform fighter game developed by HAL Laboratory and published by Nintendo.

Slippi

You can use the slippi-nixflake to declaratively install and configure Slippi with Nix, or get the AppImage directly from Slippi's website.

B0XX Emulation

B0XX controller emulation can be done via keyb0xx. A Nix package for keyb0xx can be found here.