Robocraft is a great online multiplayer game. There are multiple gamemodes that you can play with friends against other players in real time. The game is a great mix of a lot of different things as you design your own robot, test that they work and then go into battle with them against other players. In robocraft playing the game gives you exp which will over time level you up. There is also a build limit to your robots. As you level up the build limit increases until you reach the maximum level.
As far as I know the lore of robocraft is that there was a war on earth between two groups, the CF-alliance and the E14 nations. Eventually the war escalated so much they decided to have robots fight on mars instead of on a already devastated earth. These robots were controlled by super-computers (the players) and are continuing the war that started on earth.
In all the gamemodes besides elimination you can respawn. In all gamemodes besides Team Death Match there are 6 maps that the game randomely picks one of.