6pack: compressor and linker for Commodore 64 PRG files
https://oliverviebrooks.com/6pack/

6pack --help
6pack sfx game.prg

Self-contained. No .NET install needed.

Third-party formats:
  ZX0, Einar Saukas.
  LZSA2, Emmanuel Marty. zlib licence.
  ByteBoozer2, David Malmborg (HCL), maintained by Luigi Di Fraia.
