Here is my theory. I hope you like it. -----------------------------------------------------
The island is in another dimension. For this post, let's call it the "electromagnetism dimension." Inside this dimension people and/or any objects and/or the island itself have the ability to travel among many other fascinating features. This dimension shifts on its axis the same way the Sun shifts. However, the small shifts can cause some parts of the island to be in this dimension and some to be in the real world. Think of it as a cloud that gradually moves. If the cloud is over you then you are in the dimension. If it is not over you, then you are in the real world. The cloud can stand still, move gradually, move very fast or go away. Therefore, one part of the island can be in this dimension and one can be in the real world. This explains the sudden weather change as well as the constant changing between daytime and nighttime. You are switching dimensions where each dimension has it's own time, weather, etc. Plus time moves at a different speed in this "electr! omagnetism dimension." Also, you have the ability to watch the other dimension and even see yourself, i.e the lighthouse.------------------------------------------------------------------
But let's take it a step further. We already know this electromagnetism dimension can move in time and space. Right now it has engulfed the island. Imagine if it can travel more then just these small shifts. Now go a step further. We have seen the constant time travel skipping when the donkey wheel is off it's axis. So why can't this electromagnetism dimension travel in space as well when off its axis. Perhaps to Los Angeles (Losties), to the Canary Islands (Richard), to MIB and Jacob's home too, etc. When this dimension travels , all the features we see on the island go with it too since it is this dimension's characteristics, and not the islands. For example, the Smoke Monster (I will go more into him in a minute) travels with this dimension. That is why we see Jack sees Christian, Hurley seeing Charlie, etc, off the island. Now more for the Smoke Monster. Something happened to MIB where he can turn into the smoke monster. But I believe this has occurred to ma! ny people. As others have often speculated, there is more then one smoke monster. MIB happens to be a normal guy where something, which will will soon find out, made him into the smoke monster. But it doesn't mean that the smoke monster off the island is MIB in disguise. It is someone else or several people, since we know MIB cannot get off of the island. So one day this electromagnetism dimension travels and in it's path is Oceanic 815. What happens next is two things. One, the plane continues to LAX as we see in the flash sideways, and two, at the same time in this other dimension, the plane crashes and this electromagnetism dimension travels to this island we all know with the plane. This is a SIMULTANEOUS occurrence. ------------------------------------------------
Now we have the issue of people in two dimensions. Some people who are in both dimensions, the electromagnetism dimension and the real world dimension slowly start to slip between dimensions. Some such as Desmond are able to do this with some ease because they have a constant in these two dimensions. Basically they don't need to restart their human experience each time they slip back and forth and they adjust much easier then those who cannot go back and forth so easily, as is the case with a Charlotte, for example. She gets nosebleeds and eventually dies. But I believe people only die in the dimension they die in and live in the other dimension. However, this will be irrelevant for each person once that individual realizes there is another dimension, which is starting to happen with Jack, or seems to be the case with Widmore, or even with Bernard last night. Once you figure it out, you can go back and forth with no problem at all. However, until you know about bot! h dimensions, it's locked in the subconscious, such as Miles knowing Michael was lying about his name before the Kahana left port. Which leads me to my next point. Maybe those who have not realized about the different dimensions but have secret powers like Miles, really do not have special powers at all. When we saw Miles living off the island he was being paid to tell living relatives what their dead kins said. But as we know, Miles made this up UNLESS he was speaking to someone who is alive in another dimension. It can be either talking to a dead person in the real world who is alive in the electromagnetism dimension, or vice versa. Regardless, this is a small point in the overall picture. -------------------------------------------------------------------
I think those who take on another form on the island, such as MIB can only get off the island once everyone on the island is gone. Why? Simply because if there is nothing living in this dimension then the dimension does not exist. MIB needs everyone dead. All he wants to do is end his existence in this dimension, which probably dates back hundreds, if not thousands of years. Now on the other hand, this dimension brought Widmore to the island the same way it traveled over LA, the Canary Islands, etc and brought others to the island. In contrast to what MIB wants, Widmore realizes the revenue potential and wants the dimension to exits on this island forever. Therefore he needs to make sure that MIB does not kill everyone. And as we know, this is the war. -----------------------------------------
Why can't the Smoke Monster go on water? Because the electromagnetism aspect of the island does not work on water. HOWEVER, MIB works in the water as we saw last night. And he is fine in water when in the Locke form too. It is only when someone is in the form of the smoke monster that this person cannot handle the water.
Why couldn't MIB kill Jacob? I don't think this has to do with any rules. I think it is something a lot simpler. Let's say they are brothers, as people have speculated. Maybe they promised their mother they would always take care of each other. Sounds corny, however it is more for a reference on how it can be something other then rules from a game then me being serious about the reason.
Who wins the war? I think when we saw the Statue of Taweret on the bottom of the ocean with the island sunk, I think it means MIB wins the war, the island sinks, and this electromagnetism dimension dies and MIB gets to go home.
In summary, I think Lost is about another dimension, the electromagnetism dimension, which has really neat features. The dimension can travel in time/space or it can disappear. There is a war and the outcome will either keep this dimension "alive" or ti will cease to exist. MIB wins the war, the electromagnetism dimension ceases to exist, and he gets to go home. That is my theory of LOST, my friends.
Belvis