First is putting the sheer labor and time in to make a polished project, have a game worth playing and visually appealing screenshots, video trailer showing what it is and what is great about it.
Then just promote like crazy once the game is completed and released. Social media posts, comments on communities you are active in.
Paid ads can work if your game is a commercial venture but don't expect immediate payoff. Do some testing and find some ad spaces and settings that can result in net gain. Tweak the ads and do A / B testing to optimize both the ads and the game page. If your campaign is fine tuned well enough that the ad spend is profitable then go all in. If a $1 ad spend = say $1.20 in sales then you can just sort of keep ads running and cycle the earnings through for a while and build up to the point where you have a massive phenomenon. But that's not common.
I am not a game dev primarily, but I am selling assets on itch like photo based PBR texture maps and 3d assets, VFX elements and decals, so that is my focus here. And it is kind of working for me at this point or starting to, as I now have exceeded $400 in sales and have 17 five star reviews, 129 account followers, and various encouraging comments across a bunch of asset packs. Am also working on game dev in background and hoping that I can start ramping that up too soon to the point where a handful of projects are released over the next year. Which seems unrealistic maybe but given some of those date a few years back and are over half finished, it's not that crazy.
It is basically my full time focus now as of mid September. I had an Etsy shop up til end of 2024 and that is over, plus some successful gigs locally this summer (2025) that all mean I can push heavily into massive itch updates over the rest of the year at a pace that nobody has seen happening in the past. I am pretty excited about it but also aware that itch has limitations as a platform - and that it's worth branching out to sell things elsewhere too like Fab, Turbosquid, etc. It's a lot of hard work and creativity and thought and planning poured in but that ultimately is the only way to create a range of truly great products.
matthornb.itch.io <- my page.