Just to start, there are one or two people that are systematically downvoting positive reviews and upvoting negative reviews in Steam.
Since not that many people spend time looking for reviews, it makes that the one most prominent are all negative, even if more than 80% of the reviews of the game are positive.
But there is no much you can do, except doing the same, up voting positive reviews and downvoting negative reviews, at least that way things will balance.
Well, it’s good to know. I only voted on the election day so far.