Achievements such as "Slice of life" and "Chestmaster 2000" require that you interact with a certain number of interactive objects. These objects appear to all players in co-op, and seem to benefit all players when any one player interacts with them. So – when another player in my party interact with one of these objects, does it count towards my achievements?
Slice of Life
Use 50 Health wells
Chestmaster 2000
Open 2000 chests
Best Answer
Both Health Wells and chests only count for the person that opened them.
I just joined a multiplayer game to test this out. I started at 37 chests and 5 health wells, and my friend had 78 chests and 10 health wells. He opened a chest and, after a delay of 3 or 4 minutes, his updated to 79, while mine stayed at 37. The next chest I opened, and after a delay mine incremented and his did not. We found a pair of health wells, and noticed the same behavior. After a few minute delay, the person who interacted with the object got credit while the other person did not.