This odd defense challenges white's center, where white has 3 options. White will most likely play 3. exf5 and black can either exchange or go for a gambit with 3... Nf6?!. An analogue of the advance variation is possible with 3. e5, where black should challenge white with d6 and c5. White can also play 3. Nc3, where black should play 3... fxe4 which is a transpositon to the Staunton gambit. In this case, white will most likely recapture with a slight advantage or play 4. f3 with a dangerous position for black.

1.e4 e6 2.d4 f5

Wikipedia has related information at Kingston Defence.