I own the original edition of Doctor Who: The Card Game, published in 2012 by Cubicle 7. What is new in the second edition, published in 2014? Is it just different companions and such on the artwork? Or are there mechanical changes?
It appears that the majority of the game mechanics are the same, except for the addition of a two-player variant. The major additions are new cards featuring more of the new Dr. Who universe, which themselves feature different abilities. The 1st edition covers only the Eleventh Doctor (Matt Smith), whereas the 2nd edition expands this to the 9th-12th Doctors.
The FAQ page for the game says there is a new version of the rulebook, but does not indicate any game mechanics changes:
What’s different about the second edition?
Doctor Who: The Card Game second edition features the same great game as the first edition. We’ve tidied up some of the rules text and put in some more examples. There are rules for playing with 2 players, too.
More importantly, we’ve added in loads of new cards, from the Ninth and Tenth Doctors to Rose and Martha, Clockwork Robots to Ironsides and a whole bunch of new locations, like Royal Hope Hospital (now on the surface of the Moon).
The FAQ also indicates that the rules for the second edition are compatible with the cards from the first edition:
I already own the first edition – do I need to buy the second edition?
Of course not! Your game will still be just as much fun as it always has been. If you want to carry on playing you can do just that – in fact, you can download the new rulebook here, if you like.
...and even suggests shuffling the two editions together to form "one super deck."
As for the new cards themselves, the FAQ suggests that they are not just reskins of the cards from the first game:
Can I still blow up the Dalek Flagship with a Jammy Dodger?
But of course! It’s our favourite trick. You can also turn the tide of battle with an Ironside or escape in the Valiant when the going gets tough, and many more new tricks besides!
This BoardGameGeek post has the following details about the card changes:
[T]he 1st Edition has 65 cards that do not appear in the 2nd Edition. The Starting Locations are all different. There are 12 enemies that didn't make it to 2nd Edition (18 cards). Some of the duplicated Defenders have been replaced in 2nd Edition with 4 different companions. Eight of the Support cards are different. All of the Location cards are different.