The developer recently announced that they're planning to leave Early Access this summer, so they've been pushing hard on updating the game. Since then, they released a huge 0.8 update at the end of last week which promoted their multiplayer from the unstable builds for everyone to play.
I tested out the online mode and I have to admit it's quite amusing. It's nothing like Robocraft that's for sure, as you can re-build you vehicle at any time during a match. Destroying an enemy will allow you to take any remaining blocks and attach it to your own vehicle, so if you're any good you might end up with a bit of a monster by the time the match finishes.
Naturally, most of the time I ended up as a pile of blocks as someone utterly annihilated me like this:
It has two online modes, standard deathmatch and a team deathmatch. I've not had trouble joining a game, with the quick join working out fine. Seems the update did some good for player numbers, as it hit a new peak of 1.6K people online only a day ago.
It's not just the multiplayer addition that's good about this update, as they've added a bunch more blocks and they've optimised it quite a lot too. The game used to perform a little poorly, but it is much smoother with this update. Good stuff all around!