MTG Arena

Magic: The Gathering Arena is a free* digital/online PC version of the collectible card game.  Wizards of the Coast has several online offerings over the years:
- the Magic 2015 app, available for mobile devices
- Magic: The Gathering Online, which is a decidedly not free online version of the card game, where you buy digital packs, have a digital collection, can trade with players and do everything you could with the physical version
- Duels of the Planeswalkers, two releases (2009 and 2012) for PC/Playstation/Xbox that simplified several facets of the game

So what makes Arena different?
- there's no simplification of the rules
- it's free to play
- it has cards only from Ixalan set forward (MTGO has all or most expansions)
- you have different daily quests (like "cast 20 creatures" or "win 5 games") to unlock points, which you can use to open packs and grow your collection
- no player card trading and, at present, no choice of opponent (future releases will allow you to play with friends)

a game in progress; image from here (which also has a good review of the game)

screenshot from one of my games in progress

Currently in open beta (it had been closed initially), it's an attempt to reach a more casual MTG audience.  I've tried Duels and Magic 2015, and I much prefer Arena.  Deck building is pretty easy, and the gameplay is fast and intuitive.  You get preconstructed decks right off the bat, and earn more soon after.  The points you get for victories and quests are adequate to get a decent number of packs to grow your collection.  I love being able to sit down and play a quick 10-minute game (and the kids enjoy watching).  It would be great for beginners, and fun for casual players like me.  It's greatly improved my skills and understanding of different card interactions and certain game rules.  All in all, I highly recommend it.

Interested?  Check it out the trailer here and official site here.

*there are optional in-game purchases