With "few similarities" do you mean the whole almost-unique game play it received from Indigo Profecy ?
Heavy Rain is not like the tipical racing game, wrpg-indie game, etc, etc. It is a whole diferent story, however it got their base from from Indigo.
And you have read well, you were right to erase the "all" in your answer, that's what i meant with my statement ;)
The way you walk alone is completely different than Indigo. Sure there are some similarities such as QTEs, but even those are done in a way that hasn't been done before.