Magic: Arena has been trucking for some time this year and only in this past month did it enter its open beta phase. Yep, no friend codes needed, you can just jump in and play and experience what is basically a 1:1 analog of paper Magic. Outside of the fifth card problem (read: where the game doesn't sufficiently reward you for getting more than four of one card) it's been pretty smooth sailing for me so far.
As a reminder for everyone out there who wants to dive in but hasn't yet, there are a number of boosts that help newcomers along in terms of building their deck. The main bonus is that Arenadoles out beginner's decks in a rapid-fire fashion, many of which are semi-competitive, at least for the purposes of random online play.
Another big tip: you can enter the "store" section and use the code "PlayRavnica" (case sensitive) to net three free packs of the latest set, "Guilds of Ravnica" (which is going to be in competitive, or, standard play, all the way through the fourth quarter of 2020). It's a single-use code but it will work for everyone and is still active as of this week.
MTG Arena Open Beta [YouTube]