Macbeth is a minimalistic FICS client. It supports almost all FICS game types like Suicide, Losers, Wild and Crazyhouse and saves your games automatically. It is open source, you can find the source code here on GitHub
FICS is the acronym for Free Internet Chess Server. Run by volunteers FICS is completely free. FICS can look back on a long and eventfull past. It started its service as early as 1995. Beside chess FICS offers a variety of chess variations like Losers, Suicide, several 'wild' variations, Crazyhouse and Bughouse.
If you don't have an account you can always play with a guest login. But I recommend to register and create an account. FICS will track your rating, you can stay in contact with other players and join tournaments. You can register here
Updated on Oct 16 2020
Note: Now requires OS X 10.15 or later
Note: Although Finder indicates that this is version 1.0, the developer states that this is version 0.0.32