No idea how it is since I've never played it, but Blizzard's "Hearthstone" is a thing.
It's a bit complicated.
As far as RPG unlocking goes, it's pretty good. You get in-game currency by completing daily quests (destroy x minions, win x games as class or other class), which you can then use to buy booster packs of five cards each. One's guaranteed to be "Rare" (Tier 2 of 4), the rest have a predictably steep probability of being anything from Common (Tier 1/4) to Legendary (Tier 4/4). If you don't like what you get, you can also disenchant your cards into dust, then use the dust to craft any card you like, with the obvious caveat that the exchange rate is terrible and gets even worse for higher rarities.
And that's where you kind of hit a snag, because it has the usual card game habit of higher rarities
tending to be better. Certainly not exclusively, and often "better" is rather situational, but a deck with nothing but default cards in it will
usually be worse than one that was able to stuff some legendaries in there. So until you get some better, typically rarer cards in there, your decks aren't necessarily going to be awful, but they'll have a tendency to lose against someone who's able to suddenly pull a dragon out of nowhere.
Now, it does have a matchmaking system, so strictly speaking this shouldn't bother you if it doesn't bother you. You're not going to get constantly rolled by people with overpowered decks unless you're constantly beating people with overpowered decks in between. But it does tend to
feel obnoxious, when you're having a nice duel with somebody and then lose because they suddenly pull out a card that's just
better than yours for its cost.
Overall, I'd recommend it. It's a neat game, and other than having to register and install it's not like there's any harm giving it a shot.