Bit trip runner isnt a platformer. It would be easy to mistake bit trip runner as a platform game. But the truth is that it isn’t at all – it is merely an illusion. The game play is functionally identical to Guitar Hero. You have no control over the speed or direction in which you travel, you just have to press jump or duck (etc) at the right time.
It’s basically like how a shooter on rails is to a normal shooter. Much less freedom. An argument that it is a platformer is that in some cases you have decisions to make. You can either stay at the top or jump down for alternate paths. In a true platformer, the number of paths you can take is infinite because there is no time limit. If there was a time limit ina normal platformer the number of potential paths would be finite but extremely large, but being finite would put it in the same ground as bit trip runner. So perhaps platformers with time limits are fundamentally different to ones without time limits.