Robocraft Royale is a spinoff from Robocraft by Freejam Games and is open for testing. It is described as an experiment that may not make it to the full product stage but for the moment there are no plans of ceasing the development.
Many players are calling any battle royale game a PUBG rip off not realising that battle royale is now an established video game genre and not just a single game. Just like every shooter used to be a Doom clone back in the day. Even if that weren't the case, people would have a hard time considering Roboraft Royale a PUBG copycat since there haven't been any reports of robotic T-rex sightings in PUBG.
On top of that, Robocraft has fundamental gameplay differences compared to other battle royale games, such as spawning randomly on the map instead of parachuting out of a plane, you are not searching locations in order to loot weapon attachments and there is no inventory management.
You don't acquire weapons like in other battle royale games. Instead, you start off with a fragile buggy equipped with basic weaponry and then you scour the area for inactive, more powerful constructs and vehicles. It takes a few seconds but then you possess them et voila, your new weapon of mass destruction is ready to play. You can keep doing this if you uncover even more powerful mechs and weapon platforms or if your current one gets damaged.
The game also features a somewhat different combat, where you can repeatedly shoot at one part of your enemy in order to disable it. For example if you shoot a tank's cannons off, the only viable course of action for them is to run away. That is, unless you stomp them before they possess a different vehicle.
The game has just opened up for alpha testing and as such lacks several features such as team play and power ups, but the devs said these are in development.
More info and account registration can be found at Robocraft Royale website.