The game I am going to use as an example is Diablo 3. For those of you who are not aware, Blizzard put a real money auction house in to the game where they take a 15% cut on all money cashed out of the system and an extra 15% cut on any commodity transactions in the game (also $1 on all transactions). This is within a game designed around addictive tendencies, where the goal is to get people to play a 10 hour game for hundreds of hours through loot and numbers greed as mobs with ever higher numbers are presented to be killed in replays, all put in a shiny, wondrous visual and aural package that a slot machine designer would admire.
The RMAH (real money auction house) puts a whole new spin on the formula though. Apparently, Blizzard claims they didn't think many people would use it when they released the game, but now a game designer has come out and said it is a mistake that they would "turn it off if they could." (link at bottom) Most players use the auction houses (there is a gold-only one as well). Items can be and do sell for as much $250, and can be resold over and over again.
There was recently a scandal with the RMAH where a few hundred people were able to exploit a bug in Blizzard's code to duplicate gold, which has cash value in the game. Blizzard confiscated all the money involved in transactions associated with the fraudulent activity and donated the money to charity. They came out with a publicly righteous stance condemning the exploitation of the bug in their programming for personal gain. I find it ironic though, since I see Blizzard as exploiting a bug in people's programming to make billions, since their games target psychological mechanisms for addictive behavior like no other I have seen.
I would think many people consider game design a profession with the potential to enrich people's lives through artistic expression and intellectual challenge. But do some developers exploit people's psychological vulnerabilities in the same way a casino does? Is it wrong that they do? People have literally died from addiction to Blizzard games, should the game designer bear responsibility for the consequences of variable rate reinforcement working too well? Are there any ethics to game design?