A Mac version is now available for the game.
The Linux situation is a bit more complex.

BROK is fully playable on Linux via Proton (the emulation layer that Steam uses)

For now I will not put a Linux build on Steam or GOG, for several reasons:

- As mentioned, the Windows version runs great on Linux with Proton and probably WINE too,

- I'm not able to export a stable Linux version using the fastest compiler (Yoyo Compiler) so I have to rely on the slower default one.

- The Linux native build wouldn't be updated as often as the Windows build (it's hard to maintain many builds at once)
- GameMaker's gamepad support for Linux is partially broken. Most don't work correctly including the most used one, the Xbox controller, and YoyoGames support failed to provide a working solution for now.

- GameMaker only supports Ubuntu officially.

HOWEVER, if you really need a native Linux version, I have made one available exclusively on itch.io for now, with a big warning message.
In case you really need the native build and already bought the game on GOG, I'd be glad to offer you a itch.io key to get it - just reach me.

I hope for your understanding.