One thing to consider is whether you want your players actions in-game to also determine their characters' actions prior to the game. Are they guilty of the crimes they are accused of? Well, maybe. It'll depend on how good or evil they are (or if they're somehow balanced between the two). Of course, you'd need player buy in before you start with this as it requires a lot of trust for your players to let you decide such an important feature of their characters.
One way to do it is to keep it transparent and provide them with moral or immoral points as they go along and then tally up the totals. Its a bit mechanical and a more story-focused version where you make the decision holistically might work better but not every player will go for that. If you involve some form of amnesia, whether natural or supernatural, you may gain a bit more buy in. You could also provide them with pre-generated characters as players are generally more receptive to decisions made about characters that are not truly their own.
Another thing to consider is whether you want to include an 'inner monster' that the player characters can tap into to better defeat their enemies. In this videogame, you have to kill enough monsters to tap into it through some sort of inner rage meter. You could do something similar here by giving them tokens or points when they kill something but, if so, you might want to keep the required number of kills low as fights often take a fair amount of time to get through. You could have other enraged actions count as well such as verbal abuse or signs of cruelty.
This kind of game really needs symbolic monsters so you will need to generate appropriate monsters that are defined by the sins of the character or, in the case of the Suffering, the sins that are resonant with the area. Drug abuse in the Suffering, for example, is shown by crawling, emaciated creatures with glowing syringes in their eyes that attack you with their needles. Men buried alive burrow through the ground and attack you with hooked chains.
To create these, brainstorm up a list of possible signs of human cruelty that have occurred in this area and figure out the back stories behind them so you can lay clues in the game for the players to learn more about their situation. Then take those sins or cruel acts and figure out what something like that might look like or how it might attack someone.
As an example, let's look at a series of car accidents caused in a particular location by a lazy council not willing to spend the money and a reckless populace not willing to slow down. What enters your mind when you think of a car accident? Write down a list and then pick out the most poignant aspects. For me it'd be the sound of rending metal and shattering glass and the way the car sounds when its moved as the crumpled metal slides back. The other poignant detail for me would be the visual of broken glass on asphalt spattered with blood.
The next step I would take is to think about what might make that sound or leave those glass shards. How about a figure whose flesh is studded with hunks of metal and glass that drag across the asphalt? Its head mostly hangs down, as though its passed out, or perhaps has a broken neck, and it swings as it walks. It hurts you by charging into you with arms outstretched as though for a hug. Perhaps it looks adolescent. Perhaps an adolescent male to represent the stereotypical crashers or an adolescent females to represent the stereotypical passengers.
"Come on, the first one's free."
This monster also leaves a trail of blood spatters and broken glass behind it that will tear into your shoes if you don't try to avoid it. It also wears a hoody (teenager imagery) and you can only see a few bits of metal jutting out through slits in the fabric as it slouches along until it throws open its arms and you can see its mangled chest and devastated face. I'd figure out how damaging it is depending on how lethal it is. In the World of Darkness its charge would probably have a risk of knockdown that deals bashing and cuts them with one lethal. That way I could use them in small groups.
A campaign based around The Suffering, or including elements of it, should appeal to Action Heroes as you can be a badass while taking down interesting threats that change up the battle scenes occasionally. Plus, who's to say they can't change it up all the more in a roleplaying game with the odd car chase, rigged explosion, or tactically trying to set enemies against each other. Explorers will enjoy the history and strange places that are being warped by the odd situation.
Tacticians will enjoy the urban element and finding the best routes across dangerous terrain but they may also have an instinct to hole up or try to herd survivors safely rather than leaving them to fend for themselves after an initial rescue. You'll have to either discourage this early by showing in-game the tactical disadvantages of attempting to keep any safe house or pointing out that survivors are more at risk around them than away from them.
Communicators won't find all that much here for them but could still enjoy the character development and chances to interact with colourful characters so ensure that each NPC is as interesting as you can make them and give the odd rest spot for the characters to grow and develop. Investigators can be tempted along with their eye on the prize. Some grand conspiracy or question that needs answering that can be discovered along the way. Who is the bad guy? Why is this happening? Drop enough clues to keep them motivated.
You can find the trailer for the game over here. If you'd like to read the sort of tropes that The Suffering used, you can find them here.
For the next Game Translation, you have a choice of these: Left for Dead, Half Life 2, Silent Hill, Project Zero, Gears of War, Mass Effect, Dracula: Origins, Realms of the Haunting, Dragon Age 2, and pretty much any survival horror or horror game. If no one picks anything by next week, it'll be Dracula: Origins.
If you want to see the list of games I've done thus far, you can find the Game Translation series starter over here.