The unique graphical style and presentation is first class.
Unfortunately I am rubbish at platform games and I could not get past the first roof in the fire of london (about 1 screen width to the right). I couldn't get my jump to land on the roof and after about 10 attempts I had enough.
I then tried the plague one and did manage to run across some rooftops but this one was even tougher due to the insta-death rats everywhere.
At that point I wanted to punch the screen which probably means you got yourself a pretty good playformer there :).
One small thing - great idea to have the historical test in game - but it needs to be in quiet bits so that there is time to read it.