Gwent is an amazingly well developed minigame, it's very addictive and plenty of fun. A great time-sink that I enjoy playing for the sake of playing, not using it as a means of getting XP or gold, which is what usually happens with other mini-games (which is why I avoid fist-fighting and horse racing).
However, I'm pretty much convinced that Gwent unfortunately won't work as a stand-alone PvP experience unless there is significant re-working of alternate decks. In particular, Muster-based decks are simply too weak relative to spy-based decks. The power of Spy cards in particular is just too high. In a game where draw is capped, anything that allows you the ability to draw additional cards is by far the strongest ability.
Spy is thus the most powerful because it allows you to draw 2 cards for the use of one and gives you strategic control over when those cards are played, by putting them in your hand as opposed to on the board. This is the most powerful card in the game (equal in power to a few Faction powers - Northern Realms draw a card when win a round, Scoia’tael start with an additional card, Monster and Nilf ability to draw from discard pile), and is enhanced even further by the Decoy card. This is closely followed by Medic (use one draw one from discard, also can be enhanced by Decoy) and then Muster lags behind (Decoy is useless on Muster).
Muster lags behind because while it allows a lot of strength quickly, it is a one-shot. You can't revive that many cards, so the muster cards become useless once they go to the discard pile. They are extremely vulnerable to Scorch (most Muster cards summon units all of the same strength, a prime Scorch target). It's also difficult because it requires you to have more cards in your deck. You don't want too small a deck because if you end up with a lot of muster cards in your hand, you'll lack staying power, but at the same time, this dilutes your draw and lowers the odds you get the cards that you really want.
This is thus the problem: while it's not as if you cannot win with the Muster-based decks, there is simply no incentive to ever play with them. A well-constructed Northern Realms deck is close to invincible (30 cards max, 0 weather, 3 spy, 2 medic - almost guarantees that you can get the cards you need to win two rounds), even with a less than optimal draw. With this setup there's simply little reason to play anything other than Northern Realms except for flavour and experimentation - but it also means that in a PvP environment, Northern Realms would likely be very overpowered (as a side-point, the reason why Nilf isn't favoured compared to NR despite also being spy-based is because their spy cards are exceedingly worse at strengths of 4, 7 and 9 compared to 1,4 and 5).
Hence, if Gwent were to make it as a stand-alone PvP game, there would have to be significant tweaking, especially something to make Muster decks a bit more powerful/have more staying power, either that, or decrease the power of Spy cards (maybe it would have to be as drastic as reducing it to 1 card draw, so it's a use one get one, same as the medic).
Just my thoughts if Gwent were to ever make that next step. Otherwise, it's a lot of fun as it is now, so a big well done for such a great mini-game!
