Immersion in Single-Player games

Although your character may play an integral part in the game world, and while the game itself may revolve around your character, the game world cannot, and for the purpose of immersion, should not.

MBP has been playing Mafia II lately, and is a little disappointed that unlike in the first Mafia game he cannot hail a cab or catch the train.

I remember being able to catch trains in both the very first GTA and GTA3, and unlike in some games featuring public transportation the GTA trains were not always waiting for you at the station. Sometimes it was you who had to wait for the next train, but this only helped to add immersion. It made the city seem more alive if things were happening when you weren't there. Clearly the trains weren't just sitting around all day waiting for you; they actually had a schedule to keep. And that's how a game world should be. NPCs need to have lives of their own. Even if it's little more than driving or walking to the store, talking to the NPC store owner, then going back home. It's little things like that which make the world feel alive, rather than random people, standing around in random spots, doing nothing.

How often do you see people in the real world standing on a street corner all day staring off into space? Except for homeless people, hookers, and the occasional alien invasion, probably never.

One immersion-breaking part of Mafia II was being unable to enter all but the most game-crucial buildings, such as Gun Stores and Diners. Fortunately this meant I was able to take refuge from the police (just a big misunderstanding, really) by hiding in a Gun Store. Unfortunately a roving officer found me, and he too entered the store. Unfortunately, for him that is, he came in with his gun drawn, and the Gun Store Owner responded to this apparent threat by shooting him. Amusing. Unrealistic and immersion-breaking, but amusing in a random kind of way.

Also unrealistic but not quite so amusing was the very strong bias of the Police to ignore any crimes (misdemeanors, etc.) where you were not the perpetrator. If you struck a pedestrian with your car the police would chase you relentlessly, but if you were the pedestrian victim of a Hit & Run, even if it occurred right in front of the police (yes, I deliberately set one up as a test), they would turn a blind eye and go on their merry way. Unrealistic, immersion-breaking, and not quite so amusing.

Single Player games which try to immerse you within their game world, such as the GTA and Mafia series, need to ensure that world feels as real as possible, but when your character is the only person in the world whose actions seem to matter, the only thing that does for immersion is break it.