Saved games are never loaded perfectly. There is no game with a perfect load system, because memory degrades very quickly.
I'm not talking about hardware memory. I'm talking wetware. Your hard drive doesn't really degrade, but your brain can't remember what you had for breakfast yesterday.
So when a player takes a few days off and then returns to their game, their brains don't load the state perfectly. They forget the details. The longer they spend away, the fewer details they remember. It doesn't matter how perfectly the game loads from the computer's hard drive: the player doesn't remember with that level of clarity.
My favorite games are tactical games and RPGs. Things like Civ IV, Disgaea, Eternal Sonata, Brigandine. These games are "RAM heavy": they have a very complex state. You've got a lot of characters all advancing in different ways, you've got a complicated map where certain areas are critical, you've got half a dozen plans in the works.
Unfortunately, this level of detail is also quickly forgotten, especially by me. It's so bad that I literally cannot come back to a game of Civilization. I totally lose the feeling of connection I had: although I understand the overall situation, there's no real feeling of being involved. It takes longer with RPGs and tactical games for some reason, perhaps because my memory for people is better than my memory for cities. But it only takes me a few days to completely forget where I was and what I was doing.
It's possible to reacquaint yourself with your game, of course. Study the map for a few minutes, figure out the important elements and so forth. But it takes a long time to get re-immersed: there are too many pieces moving in too many directions.
I think this is probably a serious issue that many people have. In fact, I would guess that many of the people who don't play games don't play games specifically because they have a poor memory for this kind of thing. It's not a general dislike of games: the casual game industry shows that virtually everyone is willing to waste time matching colors and picking out words. But those people rarely make the transition to games with a complex, persistent state.
Their memories are probably as bad as mine. So if they load a game they were playing yesterday, they're lost.
The only reason things are like this is because game designers design games to be played straight through. That really doesn't make a lot of sense for any game over an hour long.
Any prolonged game will be saved and put aside for some length of time. The bizarre assumption we make is that when someone comes back to the game, they'll pick up where they left off. Why do we assume that?
With today's games, we're perfectly capable of determining how long it's been since someone played our game. We can treat the game as if knowledge had a half life of, say, a week. You've been away for a week? You've forgotten half the situation. You've been away for a month? You'll only remember 1/16th the situation.
Therefore, we should at least offer a slow reintroduction. If we're worried about upsetting the game balance, it could be something which has absolutely no effect on the game world.
For example, if you're playing Disgaea and we know it's been a few days since you last played, we can run a quick recap. These are the last few things you did.
If it's been a few weeks, you'll need to go more broad-scale. These are the characters you use most and their general capabilities... here's a plot recap...
There's a reason that TV shows frequently have a "Previously on Useless TV Show..." segment. People have shitty memories.
In order to do this recapping, you would need the game to understand (or at least keep a record of) the situation. The game needs to mark what details you're likely to forget, so that it can run a recap, a recentering scene, or a "semi-tutorial" that reintroduces you.
Of course, that's not likely to happen. It's not in the budget. So when you see a persistent world marketed to the "casual" audience, it's usually only surface-deep. Who cares if you forget that you were planting flowers in Animal Crossing? It doesn't matter. But forget that you can cast fireball in an RPG, you're in for some trouble.
Thoughts? Is this a problem for you? Do you think it's a significant reason people don't play persistent games?