Metal Knights is a multi player strategy game that was designed to be as intuitive and easy to play as possible. The game connects on its own to the NetMetal Server and shows you what games are started; then all you have to do is to click on a game to play in it!
Metal Knights is a turn-based game. This means that once you've taken your turn, it's up to the other players do theirs before you move again. It takes between 5 and 10 minutes to play a turn, so feel free to play in more than one game at once if you want to play a bit longer! :) Keep in mind that at first your empire is quite small and there won't be much to do in a turn until 4 or 5 turns into a game. And after 15 to 20 turns, your empire may get very huge and playing your turn may take you much more time to complete, as you may have to manage a very large number of cities and units. It's a good idea to spread out when you join games as you'll eventually have many games that will take long time to play all at once if you join them all on the same day.
Learning the game is not very difficult... but mastering it is! I suggest you start a local game and play against yourself to see what it looks like and that you follow the Tutorial to learn the basic moves and try all the features that are available. Then it's up to you to get to the highest rank, to be the next Metal Knight in the Metal Knights Hall of Fame!