This is my thoughts as well... until someone parses out the exact details of what makes Hex infringing while a game like Hearthstone doesn't I don't think I can have a full thought on it.
Hearthstone has very different mechanics than MTG though.
Whereas in Magic you can choose to block an opposing creature, Hearthstone doesn't give you that option. However, it does provide creatures that can force the opponent to attack into them.
Turns are asynchronous in Hearthstone, meaning that opponents can't interact during your turn (aside from using Secrets that still have to be played on their turn).
Hearthstone creatures don't regenerate health.
There is no Upkeep or Untap in Hearthstone, and no true Attack phase. Although one could make the argument that "At the beginning of your turn..." effects would take place in an upkeep-like phase.
You don't lose by "decking out" (drawing while your library/deck is empty).
Hearthstone classes have unique abilities.
Minor differences: Packs only contain 5 cards, classes force you to pick certain cards, etc.
Hex is a ripoff of Magic. It's not that it's "a card game". I've played other card games. I've played Pokemon and Harry Potter in my youth, Magic, Netrunner, Game of Thrones LCG(which is brilliant, by the way), Warcraft TCG, Hearthstone, and Warhammer 40k Conquest (I actually got to beta this one, which I'm pretty proud of. xD). You can't have that much in common. Every game differentiates somehow, but Hex copies the fundamental turn order to a T, along with other details such as booster pack size, card types, card mechanics, deck size, win conditions, turn order, color system, card layout, and the actual cards themselves.
Differences between Hex and Magic are minor and include items affecting card mechanics, variations in color identity, and notably cards being able to have state changes while they are still in the hand (i.e; Giving a card +2/+2 even though it's in your hand.). But again, these are all minor (and probably not all the differences but I've only played it for like 2 hours so cut me some slack.
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