To make it “realistic” you could make the player have to choose between decisions that aren’t black and white / good and evil and force the player to live out his consequences of either decision.

Do you arrest the man stealing to save his family or do you let him be? His family would certainly fall apart without him or he could go on to accidentally kill someone in a future robbery gone wrong. Both situations are less than ideal and it poses a hard choice to make, ensuring that the player is exposed to the negative consequences of either action would really drive the point home.

While I’m sure there are games out there that meet this criteria, you have to wonder why there aren’t many, maybe gamers don’t want to feel helpless or depressed whilst playing their game. Perhaps they want to feel empowered, as if they can control everything and that everything will work out in their favor.

But then again if you want to create something really unique and interesting (or a terrible mess that no one likes) you can’t hedge your bets and play it safe. I say go for the mature themes in a realistic setting, the last thing the world needs is another “You are the hero, go save the day” game.