While still in its infancy and in need of work, you’ve got to admit that it’s certainly an interesting idea – to play through the entire The Witcher 3 with Gwent as the mode of combat.
Not only does Hearts of Card mod grant you more opportunities to play Gwent, an incredibly appealing card game found within The Witcher 3, but with it the campaign remains fully playable.
Here’s an example of what you can expect:
As you can see, Gwent games are initiated the moment the player or an opponent would take damage.
Should you win, all opponents within 30 units are killed, otherwise Geralt is slain.
By allowing you to take on opponents in mass, an interesting strategy is to use your agility to have as many opponents close in on you at once, without suffering a blow.
By doing so, once you finally initiate a Gwent game, you can take down more and more opponents, depending on how many you can corral into a 30 unit radius.
More than that, the mod mitigates some of the seriousness of the The Witcher 3 and introduces the player to a very different atmosphere in a number of scenarios.
Do keep in mind, however, that the mod is nowhere near where it needs to be if it’s going to replace all of The Witcher 3’s combat and keep you entertained enough to stick with it.
The mod’s creator is implementing a number of additions and improvements, so that might be something to watch out for:
Roadmap (preliminary)
0.3 – Develop tiered loot table for cards. Scale drops based on total level of enemies in duel range. This should decouple this mod from relying on the normal Gwent progression system.
0.4 – Modify economy to be card focused. Potentially put “booster packs” in shops.
0.5 – Add special drops for significant bosses.
0.6 – Develop system to generate new cards/decks for a more smoothly scaled experience.”

Honestly I hated Gwent. Maybe just couldn’t figure it out. But loved the Witcher 3.