I had a pretty radical idea for a single/multiplayer game mode. This could be done with some friends even now on a shared server, but the rules should be followed.
Wagontrain
You start off with nothing but a compass at spawn, with several of your friends. You start moving in one chosen fixed direction, let's say North.
Rules are:
- Don't falter from the path, don't move too far away from the group. In the end, the map should look like a long, thin but knotted rope.
- At night you HAVE to stop. Create a fire if you have lighters or blocks, throw down some torches, then defend yourself against the onslaught of enemies until sunrise or near sunrise - whenever you feel it's safe to keep moving.
- if you find a cavern as you travel, you HAVE to stop. At this point you can build a settlement around the cavern and mine until you feel like you've wiped that mine clean. At that point, real life hours, days, maybe months later, you move again.
- you can ONLY put beds in settlements, not camps. If you die, you return to the last settlement or spawn and have to go catch up with your friends.
- when you leave a settlement, you can only take what you can carry until Notch adds in a caravan or pack mule, or mods do. You have to leave what you can't carry behind. Or just share the load with others who might not have as much.
- if you have railroad tracks, you can link settlements, just try not to waste too much time building bridges. Night is falling!
- as I said, when you look at the map, it should be like ------O--------O-------O with the dashes being the thin trail and the "O"s being the settlements you build.
- you can leave people behind if they'd rather stay in a settlement for a while, but if they get bored they should move on and find you again. What you can't do is leave people behind because they're building without having found a cavern. Don't leave a man behind! Don't slow down! Find a cavern!
I don't know when the game would stop, this is all I have brainstormed today. But reading two books: one on the Oregon trail and the other being Lonesome Dove about a cattle drive, I think this would be totally awesome to try out.