In the BGE you can't create a subclass with more than 1 argument like : "player = Player(owner, 10)"
I have modified the py_base_new to check only the first argument of args tuple.
Now we can do :
class Player(types.KX_GameObject):
def __init__(self, gameobj, life):
print("create new player :", self, ", life :", life)
player = Player(own, 50)