Last year, I talked about single elements that can be the main focal point for an entire campaign. After giving some more thought and a comment from Ravyn. I would like to expand more on the list of one things that you can based an entire campaign on.
This was pointed out by Ravyn. An entire campaign doesn't always have to take your players outside one environment. It could stay in the same place as long as there is always something to do or something is constantly happening around the PCs.
Cities are a good example of creating a one location campaign and there are published settings out there that takes this idea (Ptolus, Sharn, Waterdeep, City of Brass) but it is not always limited in urban areas. It could also be wilderness based such as an island, a forest, a mountain, a plain or even a dungeon (World's Largest Dungeon, Undermountain, Castle Greyhawk).
One location campaigns sounds very much like sandbox campaigns and the way to run this is to maintain the dyanmics of the setting while you keep surprising your players all campaign long.
This may sound odd at first but there is quite a few potential of creating a campaign where all players are only allowed to play as one race. I don't know how common it is but I have heard alot of people only allowing humans in their campaign.
By doing so, they increase the value and mystery of the other staple races and this allows the GM to expand on them in different directions that wouldn't be balance if they were playable. In a human only campaign, elves could be elevated to wield more arcane power and appear more feyish or dwarves do really stay in their mountain homes and never leave them which creates an adventure for the human players to find them.
Another potential benefit of playing in a human-only campaign is that roleplaying can become easier. Some players and newbies could find it hard to roleplay as any other race because they themselves don't think or behave like them. In the end we are just humans pretending to be elves and dwarves (or half-orcs) so why not just be ourselves?
However, this idea isn't limited to only humans. What not try playing a campaign where you're only allowed to be halflings? Or a monstrous race?
One Power Source
Alright, the idea sounds very 4E-ish but it is already being done in other RPGs before it, just look at any of the World of Darkness RPGs. In 3.x days, you could build an entire campaign out of the Psionic Handbook, Tome of Magic or Book of Nine Swords.
With new 4E classes coming out almost by the buckloads that would most likely let each power source cover all the roles, it would be interesting to see how different classes from the same power source match up with or against each other.
Certain power sources could inspire themes that won't normally be as effective when used in a campaign that also allows other power sources. For example, a combat tournament or arena to find the best martial character in the world holds more significance and would not ostracize any players in a martial power source only campaign.
This normally works as a campaign setting's background. All post-apocalypse campaigns are based on this. In fantasy, a recent example is the Spellplague in the Forgotten Realms. Although world destruction is a very common and dramatic incident to have an entire campaign based on but there could be other more mundane incidents that could affect the campaign setting as well.
In modern settings, 9/11 is the catalyst of war on terror and it could be the incident which could spark a international anti-terrorism campaign where players either play as spies or an international elite squad of counter terrorist.
The same could be done with medieval fantasy setting where the king is dead and a civil war of succession is erupting in the campaign setting. This was done in Eberron with the end of the Last War but it sets the stage for a campaign centered on fantasy espionage, politics and intrigue.
Incidents don't also have to be disasters or tragedies, sudden dramatic and perceived to be positive changes could still be used to create conflict. Perhaps a recent scientific or magical breakthrough or discovery in medicine could lead into a potentially good effect towards the campaign setting but there is also a dark side of using the drug.
The most important thing about these campaigns is that the details of the incident itself has to be clear and its effects to the campaign setting (good or ill) has to be prevalent enough to change the life of those in the setting or how the campaign is run. They are usually more memorable if the incident is named like The Rapture or The Revolution.
Well, that's it for now. Anymore one thing campaigns that you would like to share?