Players of Diablo III have, for a time, shied away from cooperative games to play alone in spite of the game's heavy emphasis on cooperative gameplay.
The reason for this was because monster damage would increase exponentially with each additional player, making difficulties like Hell and Inferno close to unplayable because even common monsters could kill players in a single hit.
Blizzard noted this issue and has since released a small patch—or "hotfix"—to deal with the problem. The patch went live on Sunday. It reads as follows:
In cooperative games, monster damage no longer increases when additional players join the game. Please note that monster health will still scale based on the number of players in a party.
Players who join in cooperative games will no longer be killed in a single hit if they're decently geared, and they will not have to play alone just to survive the campaign in harder difficulties.
In addition to the changes to the difficulty scaling, the new patch adds a couple of bug fixes, one of which prevents players from repeatedly turning in quests to receive rewards.