So, what is Infinity Wars, and why should you try it over any other TCG? First off, let's get this out of the way: the game is pretty complex and your enjoyment of it may vary depending on your TCG experience.
Either way, the basic game mechanics should be familiar: players have a health meter, draw a card each turn, cards have a resource cost, you get 1 resource per turn. (I will not be using the game's own terms because there's no point in doing that if you have never played it).
There are creature cards, spell cards, artifacts and field/location cards, which all work in a similar way to MtG's equivalents.
Cards have attack and defense values, and they do not gain their defense back at the end of the turn. Now, here's the part that sets Infinity Wars apart from others: the zones and simulaneous turns.
Let's start with the zones. You have a Support Zone, a Defense and Assault Zone and a Command Zone.
The Support Zone is where a creature will go if you play it from your hand. Call it summoning sickness if you want, it's what prevents you from playing it on the battlefield right away. You can keep a creature there for as long as you wish, and you can also retire your active creatures there at the start of your turn.
The Assault and Defense zones are where creatures attempt to attack the enemy's health or defend their player respectively. When attacking, you have to go through your enemy's defending creature pool if you are to deal damage to them. If the enemy has 5 creatures and you have 4, no matter their stats, you will not manage to attack his health (assuming all creatures don't have some form of text that changes that).
However, the opposite is not true. If you have one 1/20 creature defending and the enemy attacks with 20 1/1's, everything will die at the end of the turn.
So how does battle work? The answer is pretty simple: it is done automatically. Once you place your creatures on one Zone, they will all attempt to attack or defend starting from the leftmost creature. You can change the order or the Zone during your turn at will, but not after the automated battle has started.
Before I continue, I have to mention that one player gets Initiative each turn alternatively. You will see what that means very soon.
And that's where the simultaneous turns come in. While you were planning your trades to be statistically in your favor, the enemy has been doing the same. When you both click "end planning", spell effects will be triggered first (and, if both players used a spell, the one with the Initiative has his trigger first), and then, if any creatures are left alive, the battle begins.
If you are a little confused by this, don't worry, the battle phase is very easy to figure out once you actually play the game. As a side note, you can get amazing trades if you position any creature that gets buffed correctly. If you have a 4/4 that heals itself for 2 every time it kills something, it can kill an infinite number of 2/2's.
Remember the Support Zone? If you think that an enemy is going to use a spell that kills one or more of your creatures, you can retreat your vunlerable creatures back into it for the turn, and the enemy is going to completely waste his spell.
This creates a lot of "mindgames" during matches, and you feel incredibly satisfied when you manage to outsmart your opponent in such a way.
The Command Zone contains any 3 cards in your deck that are chosen prior to the game's start. They are revealed to both players to make the mechanic more fair. Their cost is the same, but you can put them directly into the Assault or Defense zones without making the transition to the Support Zone. If you do not do that, they stay in the Command Zone. So how can you use that to your advantage? Apart from playing powerful cards quickly, you can let them build up stats if they have a passive ability (+x/+x for every creature that dies, for example) or activate their abilities safely (pay x: deal x damage to a creature, for example).
Finally, there are two more small mechanics that make the gameplay more varied: cards have a Morale cost, which is a secondary resource. When a creature with 2 morale dies, you lose that morale. If you have 0 Morale, you lose the game, exactly like your health. This is useful if you are running a defensive deck that doesn't have much damage, and makes tanking and stalling strategies more viable. The last mechanic is the Trading Post, where you can use your leftover resources to shuffle a card (or your hand, on turn 1), draw a card or increase your max resources by 1. This means that you have always something to do with your resources even with a bad hand, and it also means that some cards can cost more than 9 resources (which is the normal maximum) and have absolutely gamebreaking effects.
Now that we're done with the game's rules, let's talk a little bit about the game itself. It has a client of its own (like LoL, for example) where you can play, buy packs, edit decks, see your achievements and tweak the settings all in one. The client is a little slow, and I have often encountered some bugs if I click things too quickly before they load properly. There are also some minor connectivity problems, but most of the time you are not going to lose any of your progress. My biggest gripe with the UI is the deck builder, it seems really clunky and counter-intuitive to me. Also, more customization options for text size would be welcome.
You can play a wide variety of game modes, ranging from an impressively large campaign with voice acting and a storyline (something a lot of TCG's shy away from) to a ranked mode and a rift run (which is something like random draft, or Arena in Hearthstone). There are some free decks to choose from each week, and some of them can stand on their own against custom decks, which means a newer player can have a shot even if he hasn't accumulated many cards on his own. You can buy packs with in-game money or real money, and the pricing model seems fairly standard. There is also card trading, which is a major plus for me.
There are multiple factions in the game, and their gameplay mechanics and art style are really varied and interesting. All cards also have Purity, which means that you need to have at least x of a certain type of Commander to be able to play them. For example, the most extreme rush cards would require 3 Flame Dawn Commanders. Some of the game's 9 factions include:
War40k-inspired demons that have chaotic and destructive discard and exile effects.
Cold and calculating machines that buff themselves or deal long-range damage.
Anime-style tech angels that fly over your defenses and ascend to higher forms.
Mechanical zombies that eat creatures so you can play them yourself next turn.
The card art is really cool and fitting for each faction's ideals, and so are the animations. Some of them even go as far as telling a small story in a few frames, which really shows the work put into each individual card. Speaking of which, there are a LOT of cards in the game, I am stil discovering new ones every day.
The battlefield in which you play in is 3D rendered, and can even change if you play a Field card.
The music and sound effects are not exactly brilliant, but you will probably not notice them anyway, as anything too distracting would've been detrimental to the game.
As a final thought to close this colossal review, if you are somehow still undecided, I have to say that this game deserves to be tried at least for its attempt to introduce new mechanics to a fairly tired genre. It has MtG's complex mechanics, strategic battles and card trading while also boasting nice visuals and a free-to-play model.
I'm glad I found it, and, even though it's not perfect, I think it deserves way more recognition.