We have a niche game, and it's struggling to gain traction on Greenlight.
Race The Sun is like a mashup of Temple Run and Star Fox. One could call it an "endless racer" - but it doesn't necessarily appeal to the "racing" crowd. One could also categorize it as "Action" - but it doesn't have any combat.†
It's hard to describe - and it's hard to sell with words and pictures. Consequently, we've struggled to get much media attention, and we've struggled to get a ton of attention from voters on our Greenlight page.
Nevertheless - we're confident we have a great game on our hands. People love the game when they play it. It has an unparallelled sense of speed, a unique asthetic - and we've got some plans for social features that will set it apart: a cooperative relay race mode and server-hosted mods that we believe will give it a lot of longevity.
We've also run a successful Kickstarter, and the (very outdated) demo version on Kongregate has nearly half a million plays and is highly rated. The latest internal beta boasts an average session length of 2.5 hours.†
So - here's my suggestion for Valve: Give niche games like this a chance, by letting us share the game's engagement metrics with them directly.
In other words - let us host a demo version of the game through the Steam service, and measure user engagement - session length, player retention, etc. Give us enough API to toss a "Rate this Game" pop-up in front of the user - and then consider these engagement metrics along with the raw votes. They're probably a much better predictor of future sales than raw "yes" and "no thanks" vote counts.
Aside from these ideas - perhaps people have more ideas for Greenlight success for niche games like this? I'm all ears!†