GWENT: The Witcher Card Game

This isn't as daunting as the description makes it seem. You can win matches without killing any units; the game only requires you to have more strength to win a round. As long as you are careful, you can also attack enemy units and weaken them quite a bit without killing them.

You do need to actually win the match, however. It's not significantly harder to win without killing, but killing does make it easier. For tips on winning and the meta of the game, I'd suggest watching pros on YouTube. There's a lot to take in.

You can also get this if your opponent backs out and forfeits the match, as that counts as a win too. That is how I unlocked this achievement.