Depends on how you count it. There is a multiplayer mod, nebula. Before the latest major patch (introducing enemies), it worked pretty flawlessly. I only had some glitch with infinite bot charge sometimes but nothing game breaking. Very rarely it randomly stated an error and had to re-join the host. Only downside is that you need to (and must be able to) port forward yourself! Otherwise playable like if it was singleplayer.

For the latest version, last time I checked, there was still no official release. But a work-in-progress I could have potentially downloaded and compiled myself. But since my motivation to play was already low I chose not to figure that out.