It has been complained about many times and I'm sure in annoys most of us. Your opponent gets dominated very quickly but they surrender with just 15 hp left. I'm sure no one has suggested this yet so here it is. Make the achievements such as, winning with all 3 characters left, able to be completed if your opponent surrenders after x amount of turns. Maybe 6 or 8 turns. This will fix this problem and prevent it from being completed if your opponent surrenders without a fight.
or make an achievement tree - "playing *** games without surrendering"
that would work alot better
That one could be added to. These 2 combined would be awesome. If it was just what you suggested then people would continue to surrender after they completed it.
I think it is a great idea as well. Also, you could say if your opponent surrenders when they have only one character left with less than 20-30 health.
Nice idea. But maybe 50% health left.