‘Death In Heaven’ reveals that in the event of full-scale invasion an Earth president is inducted immediately, with complete authority over every nation state. Their conclusion that the only practical choice was the Doctor.
This obviously has ramifications for an adventure featuring an alien-invasion from 2016 onwards. Even if your campaign doesn’t feature the Doctor it gives some insight to how the world governments now react to invasion.
Firstly is the conclusion that the Doctor is the most practical choice. In the past he has been treated with suspicion due to his alien origins so it is surprising that the majority of voters decided that a non-human could be trusted to protect and lead humanity.
There is also the assumption that the Doctor will be present during an alien-invasion. While true that he is frequently on hand during a crisis this isn’t always the case. Indeed Torchwood ‘Children of Earth’ indicates that he isn’t always present during alien incursions not to mention future invasions such as those depicted in ‘Dalek Invasion of Earth’ or the references to the Martian or Cyber Wars.
Should there be an alien invasion resources would have to be spent trying to locate the Doctor. While we’ve seen that in the 21st century surveillance and phone tapping has been useful to locate the Time Lord this can’t always be relied upon.
UNIT PCs could find themselves assigned to locate the Doctor during an invasion. They could have little to go on and there is always the chance that he isn’t actually there. This really stacks the odds against them with a very short time limit.
It could be that rather than searching for the Doctor they send a message to him, perhaps using the space-time telegraph. This would force the Doctor to be on call, responding whenever there is an invasion.
Kate Stewart is very specific in that the Doctor is only Earth President while on the plane, Boat One. This condition could be in place to ensure that his powers are limited to the duration he is onboard and prevent him from leaving unexpectedly.
The world leaders are waiting for his orders, which does mean that in order for this to work communication systems need to be in place. We never see the Doctor make use of this authority so we don’t know how effective it was.
One can imagine that following the events of ‘Death In Heaven’ that the various world leaders were dissatisfied that they received no guidance or support from the President of Earth.
If the Doctor wasn’t available or they decided to vote him out of office who would they choose instead? No world leader could be trusted not to exploit the role to favour their own country (aside from Barack Obama given his reputation in ‘End of Time’). Indeed, as an outsider, this is something that the Doctor had in his favour (although he still focused on the UK).
Timelord or alien PCs could be good alternative candidates, especially if they have a proven record of foiling alien invasions. This could be a good permanent position for stranded or exiled PCs.
It is possible that someone from UNIT might make a good selection or someone that has studied previous invasions and has come up with new strategies to deal with them. Someone smart, charismatic and trustworthy could secure the position.
A campaign or series of adventures could be based around a prolonged alien invasion that takes months or years. The PCs could take the role of the Earth President, world leaders and their support staff.
While every nation has agreed to follow the orders of the Earth President in theory what would happen in practice is they disagreed or his choices would negatively impact their country? What if they felt one country was receiving more aid or that they were sacrificing too much?
This could lend a more political edge to an alien invasion story. How do the PCs save the world while still maintaining diplomatic relations with other countries? Once the invasion is rebuffed how do the individual countries rebuild and heal from the damage caused? Will the Earth President retain his position or will there be a new vote?
Putting so much power in the hands of a single individual is also potentially dangerous. If they were killed it would be a huge blow to morale and disorganise the world. The flying Cybermen surely exposed the tactical flaw of an unescorted plane so how else do they protect the President of Earth?
There is also the danger that the Earth President could be impersonated by a shapeshifter or that they have their own agenda. An adventure could be based around a false invasion engineered to allow the Earth President to take over the world.
PCs can discover just how long this new position remains as they explore the future. When dealing with future alien invasions they discover who the current Earth President is during the crisis.
This could be a good way to keep the Doctor in the background. The focus can remain on the PCs because the Doctor is currently occupied leading the world, requiring them to be on the ground dealing with things directly.