Complex sentence: Tunney has been a vocal supporter of the Gamergate movement, which says it supports "ethics in gaming journalism", and opposes incorporating ideas and perspectives from progressive social campaigns such as feminism into video games.
Split into simpler sentences: Tunney has been a vocal supporter of the Gamergate movement, which purports to be about "ethics in gaming journalism". Tunney opposes incorporating ideas and perspectives from progressive social campaigns such as feminism into video games.