Basically a multiplayer mod for the game Transport Tycoon Deluxe.
I got into it about a year ago and have been hooked ever since.
It might be a bit complicated at first, but if you stick with it you'll see how much it pays off in the end.
The game is basically this: You're starting a company. You don't really have much of a goal, except making money and being cool. The easiest way to start out (in my opinion) is with coal. Just set up a train station from the nearest power station to the nearest coal mine and wait until you have a lot of money to expand on your operation.
A quick way to gain money in the game (besides loans) is airports. They produce a ridiculous amount of income. and I do mean ridiculous. A couple friends of mine were playing with me, and we were all in the same company. But one of them left, rejoined and formed his own company. By that time, we were way ahead of him and focusing on our trains. He built a few airports here and there, and before we knew it, he had at least $10,000,000 more than us. After we had been playing for a few hours.
Anyway, there are a lot of ways to make money in the game. Before starting, you select a game year (I usually select 2500 and up, because that's when you get the maglev, which is the best kind of train you can have but if you are really serious about it, you can start in the 1900s and use steam/coal powered trains) and you select the type of terrain you want to play and other options like this.
Then you can start either using boats, trucks, trains or airplanes to carry your cargo from place to place making money along the way. The easiest being airplanes, but the funnest (in my opinion) being trains.
Boats are a little messed up in the game and don't always work properly, so making a boat only based company doesn't often turn out good. But using them for aiding a train or airplane based company is a good idea.
Trucks are slow, they can't carry much cargo. But the roads are easy to navigate, since they go both ways and you can have a lot of them at a time.
There are different ways of making money, for example you can bring wood from a forest to a sawmill, and get paid for doing so. Keep in mind you get paid based on how far the cargo has traveled, so bringing wood from 1 side of the map to the other takes a lot longer, but it pays off in the end.
You can also work with oil (bringing it to a refinery), passengers (bringing them from town to town), producing goods (and delivering them) etc etc
In conclusion, a great game to play with a few friends. Great place to also meet new friends, but also fun to play alone (just not "as" fun)
finishing up with a couple screenshots (not all mine)
*side note; there is also an iPod Touch application for the game. I've got it, and it runs great. The only problem being that the buttons are so small I often press the wrong one or lay a track down in the wrong position. (a nice alternative would be using a small stylus, but I have yet to find one small enough to press the buttons on the interface correctly)