I've been chatting about Doctor Who to my friend via Email, his last message raised some interesting points.
You were right, the Time Lords have been corrupted. Destroying the universe in order to eliminate your enemies is a bit drastic, even for Rassilon. BTW, Gallifrey has been revealed to be much larger than Earth, but we know its gravity and surface conditions are fairly similar. It can’t be very dense, or the Time Lords would be built like the Squats in Warhammer 40K. Is it really their world of origin, or a planet they have engineered to suit themselves?
This raised some points in my own mind, points that had ramifications in regards to the RPG as well.
I'm wondering if it is indeed the original Rassilon, or some psycho who's took on his name. Rassilon was a power hungry maniac who saw the error of his ways (his change of heart was revealed in the 5 Doctors) this guy seems to be the Rassilon of old - if he's back, as he was - then he would be IMMENSLY powerful - perhaps the Time Lords broke the laws of time and returned Rassilon before his change of heart(s) just as they resurrected the Master to enlist his help.
As we now know the Time Lords aren't dead, they are "Time Locked" left to die at the end of the Time War - with Rassilon (again IF he is the original) being the powerful genius he was reputed to be - will they stay their for long.
In "Father's Day" the Ninth Doctor remarks that prior to their supposed destruction, the Time Lords would have prevented or repaired paradoxes such as that which attracted the Reapers to 1987 Earth.
In "Rise of the Cybermen", the Tenth Doctor mentions that while the Time Lords were around, travel between alternative realities was easier, but with their demise, the paths between worlds were closed.
It was only a matter of Time (no pun intended) before the Time Lock was circumvented, and how long before it is shut down for good.
To 'eek' out a little more information about whats going on, we need to look at some Doctor Who "Fluff" regarding "The Other".
A legendary figure in Time Lord history, the Other does not appear in the television series itself, but is mentioned several times in the spin-off media based on the programme.
The Other was intended to be part of the backstory of the television series during the Seventh Doctor's tenure and part of script editor Andrew Cartmel's so-called "master plan" to restore some mystery to the character of the Doctor and eventually reveal the character's origins. However, although hints of this backstory were liberally scattered through Seasons 25 and 26 of the series, the suspension of production in 1989 meant that the "master plan" never paid off on screen. Elements of it, however, were used as part of the background for the Virgin New Adventures line of original Doctor Who novels. Eventually, most of the details were revealed in the last Seventh Doctor New Adventure, Lungbarrow by Marc Platt.
As with elements from other Doctor Who spin-offs, the canonicity of the following with respect to the television series is open to interpretation (though a LOT of Who Fans insist there is no real canon - EVERYTHING Russell T. Davis has done supports Doctor Who "History").
The Other was first mentioned in the novelisation of Remembrance of the Daleks by Ben Aaronovitch as a shadowy figure in Time Lord history, one of the founding Triumvirate of Time Lord society after the overthrow of the cult of the Pythia that had, until then, dominated Gallifrey. The other two members of the Triumvirate were Rassilon and Omega.
Of the three, the Other's origins are the most obscure, with the circumstances of his birth and appearance being a mystery. Like Rassilon, various contradictory legends surround the Other, some hinting that he had powers surpassing that of Rassilon or Omega, and some even suggesting that he was not born on the Time Lords' home world of Gallifrey (The New Adventure Human Nature Novel - which was eventually filmed for the TV Show, obliquely implies that the Other was a Victorian scientist who built a TARDIS-like craft and travelled to Gallifrey when its people were still primitives - I reckon he was the Time Traveller from the HG Wells story LoL) this 'Human' link is further supported by the series, how would it even be possible to re-write a Time Lords DNA to make him human if they weren't related in some way to Humans - the ability to regenerate is a granted ability (all Time Lords are Gallifreyans but not all Gallifreyans are Time Lords).
Even his name is lost to time, which is why he is simply referred to as "the Other". A minor Gallifreyan festival known as Otherstide is celebrated yearly in his honour. This festival falls on the same days as the Doctor's name day.
When the Pythia was overthrown, she laid a final curse on Gallifrey that made the population sterile. To ensure the continuation of their race, Rassilon created the Looms, machines that would "weave" new Gallifreyans out of extant genetic material - further examples of Genetic Tampering.
Omega apparently died (only to return in "The Three Doctors" and "Arc of Infinity" - Time Lords have a tendency to do that LoL) creating the black hole which provided the raw power needed for time travel, turning the Gallifreyans into Lords of Time.Some accounts suggest that Rassilon misled Omega into believing he would survive this mission (further evidence of Rassilons less than friendly history).
Rassilon and the Other were left to pick up the pieces, with Rassilon harnessing the nucleus of the black hole to create the Eye of Harmony and becoming virtual dictator of Time Lord civilisation. As Rassilon's rule became more oppressive, the Other knew that his own days were numbered.
The Other first ensured that his granddaughter Susan (the last child to be naturally born on Gallifrey - now if Susan was naturally born, she theoretically wouldn't have all the Time Lords granted abilities - which is why she could settle on Earth after "The Dalek Invasion of Earth" she would be long lived, but not able to Regenerate) was safe, sending her to the spaceport to escape off planet. Then, in a last gesture of defiance against Rassilon's rule, he committed suicide by throwing himself into the Looms, mixing his genetic material into the banks.
Eons passed, and the Looms became integrated into the great Houses of Gallifrey. Eventually, a new Time Lord was born to the House of Lungbarrow, who would become known as the Doctor (who is IMHO a genetic re-incarnation of The Other, but more of that later).
Disenchanted with Time Lord society, the Doctor stole a TARDIS, intending to explore the universe. However, inside he discovered that the Hand of Omega, the stellar manipulator Omega had used to create the Eye of Harmony, had followed him on board, somehow recognising inside him one of its creators. Although time travel into Gallifrey's past was strictly forbidden, the Hand overrode the locks that prevented the TARDIS from doing so and took the Doctor back to the Old Time.
There, a year after the Other had vanished into the Looms, the Doctor found Susan wandering the streets of the city — she had never made it to the spaceport. Like the Hand, although the Doctor did not look anything like the Other, Susan recognised that there was a connection, and when she addressed him as "Grandfather", both of them knew that it was somehow right. The implication was that the Other had been genetically reincarnated as the Doctor, although how much of the Other is in the Doctor and how much he remembers of his past life, if at all, is unclear. Susan and the Doctor then left in the TARDIS to travel through time and space.
All through the back-story, there are little hints and links to Humanity. We are the Time Lords (such hints are littered throughout televised Doctor Who stories - please post responses if you find them LoL).
Time Lords appear human, but differ from us in many respects. It is a common misconception that all Time Lords in the classic television series are white adults. A Black Time Lord appears as an extra in "The Deadly Assassin", and in "Planet of the Spiders" some white actors used yellowface to appear Tibetan. A black Time Lord appears in the 2007 episode "The Sound of Drums". In addition, Time Lord founder Rassilon was portrayed in several audio plays by black actor Don Warrington (a little 'Vaderesque' as it is established that Rassilon is caucasion). An 8-year-old Gallifreyan child (implied to be the renegade Time Lord known as the Master) was depicted in "The Sound of Drums" and appeared identical to a human child of the same age.
For Fans to presume that Time Lords managed such a similar evolution to ours on Earth WITHOUT some external factors influincing it - a tained gene pool, colonists, they are our descendents etc - the options are as endless as time . . . . .
If a being had two hearts as a natural part of evolution, they would look a lot less Human than the Time Lords do.
Its likely that their Chest cavity would be a lot larger, to accomodate the hearts and the lungs themselves (I doubt if they would be as skinny as David Tennant either LoL) or the Lungs would be 'pushed' down giving them a 'pot belly' look (disenters with this logic will cite the "who's to say with Alien evolution" schtick - but for them to LOOK Human, they would have to have a similar - if not exactly the same - evolutionary path) in reality, with an extra pump pushing the blood around, a Time Lords Blood Pressure would be higher (not lower as it is in the series) which would generally leave them with either visable or bulging veins and eyes.
Lastly, the head of a Time Lord would most likely be bigger too - to accommodate the increased blood flow and to release the increased temperature - necessary to stop the brain from boiling in its own blood or simply burning up with fever - which is mentioned in the series, when referring to Donna.
HOWEVER if the Time Lords are genetically manipulated, an extra heart (complete with an efficient compacted respitory system) - a lower blood pressure would be 'in line' with that - if a second heart was implanted, you could indeed have lower blood pressure - as the 'push/pull' effect of the hearts would still maintain a healthy circulatory system.
The lower blood pressure (and lower body temperature) would 'save' the veins and eyes from having to bulge, and reduce the neccesity for an enlarged cranium - as the brain would no longer be under pressure and wouldn't boil in all that high pressure high temperature blood. Of course these are only suppositions, but they make a lot of sense (at least to me they do he, he, he).
All these 'modifications' are linked to Time Travel in some way - the simbiotic link between a Time Lord and a TARDIS being the obvious one.
Time Lords are "suited to Time Travel" yet they 'evolved' in an environment without Time Travel - its more than likely they were MODIFIED to suit the Temporal requirements.
Its stated that (in the 5 Doctors) Time Lords were virtually immortal originally, and this immortality was replaced with the Regeneration ability to avoid corruption - further confirmation of genetic modifications being performed.
With regards to Gallifrey itself. Gallifrey is pretty much hollow according to some of the fluff I have read, and because of that it would have a smaller core and support an Earth like gravity.
Its atmosphere is thinner, but less poluted than ours- so around the same Oxygen content as modern Earth.
It is a generally cooler environment (which is supported by the 'hollowness' and smaller core) than Earth, and yet is in a system with two Suns. Perhaps its at a greater distance from the Suns than we are from our own.
Heres another quick thought - if Gallifrey was indeed dead an gone - how does the Doctors TARDIS work.
Within the great Dome is the Capitol; and in the Capitol is the Panopticon - under which is located the Eye of Harmony, the nucleus of a black hole. The Eye provides the power required for time travel (mentioned in "The Three Doctors", and "The Deadly Assassin"), and all Time Lord TARDIS' draw their power from it - if Gallifrey was destroyed - the TARDIS wouldn't work.
In the "Rise of the Cybermen" the TARDIS is cut off from our reality and loses all power - so the TARDIS was still linked to the Eye of Harmony in some way.
Just some thoughts which I thought might be useful in planning an extended Campaign.