Let’s talk about demographics. According to SteamSpy, the overwhelming majority of players on Steam do not buy many games. In fact, they buy 4 or fewer. If they’re in this demographic, you’re not trying to market your game to them. Hardcore gamers, the ones that play major hits or buy a multitude of indie games are very rare when compared to the overall audience. One percent of Steam gamers own a third of all copies of Steam games, and 20% of Steam gamers own about 88% of games. There are over 700 million PC gamers, but if you’re making a game for Steam, you’re only striving for the attention of only about 1.3M gamers that are buying the majority of games.
If you’re selling your game on Steam, you should appeal to the hardcore demographic if you want to get any traction whatsoever. This means… roguelikes, RPGs, super niche visual novels if that’s your target audience, or even meme-inspired games that may appeal to the right crowd. But, don’t do casual.
So now that you’ve decided on a demographic to target. What do you prioritize? Focus on the visual aspect over everything else. If you’re horrible at this — find an artist and partner up, buy some asset packs, or contract an artist. After the visuals are polished, focus on refining the core gameplay loop. Make sure that the game is fun. Test it out yourself or with your friends. If you and other players who test the game are not enjoying it…chances are it’ll look bad in a trailer and won’t be fun overall for players who check it out. You’re trying to convince both Valve and the Steam playerbase that your project is worth being sold and played by the masses on Steam, so make sure you have a project that lives up to Steam’s standards!
There’s a saying in the game development community that for every hour that gets spent implementing a new feature, 10 hours should go into refining, polishing, and iterating on the new feature. This isn’t just a joke or a gross misrepresentation — this is reality. Listen closely though. Polish doesn’t mean what you think it means. It doesn’t mean doing what you think looks good.
Get feedback from others, draw inspiration from games in similar genres, and make sure that you watch Vlambeer's The Art Of Screenshake on YouTube. Be critical of your own design, and be sure that your game feels and looks “alive” visually. Build visual interest with enough special effects, and when in doubt, add more screenshake. Target the right audience, and make sure you aren’t shooting yourself in the foot by releasing a game that has no chance at all in the market.