Snow machine, home made fun type!

the motor must be in the wheel hub area... but I don't see how it is steered, unless it's differential engine speeds, it looks chainsaw motors and twist throttles. I don't recall where I was tipped off to this from, for a couple other very interesting home made snow machines: http://parkoffka.ru/item/2010/4/15/samodel_nyi_snegohod_12_fotografii