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Try it ;-) 

Of course, fantasy setting is the most popular and there is always a lot of demand for it, however, because of this, there is a certain overabundance of fantasy-style assets, while there is a lot less for sci-fi (you can check this by comparing the output in search queries by tags here on itch.io). But in both settings, it is possible to use common archetypes, changing only the details: you can change an archer to a sniper, a knight to a rifleman, the thief to a spy, skeletons to robots, spiders to robospider, Kobolds to xenos and the wizard...well, any highly advanced technology looks like magic))) Therefore, this is one of the growth points.

For example, you could try experimenting with cyberpunk: you have a good sense of color, and color is one of the key features of cyberpunk aesthetics serving as a narrative tool (a strong contrast of dark with vibrant neon lights and futuristic glow, glitches, symbolism in minimalism and so on, that's exactly what you can do well). Well, the dystopian atmosphere of "high tech & low life" and neon noir is great for an adventure game (including in the scenery of "dungeons"). And that's the first thing that came to my mind looking at your palette)))

And to get a better feel for the cyberpunk aesthetic, you can try watching anything from Ghost in the Shell (anime), Blade Runner, Tron, Dredd, Robocop, Total Recall and even Cowboy Bebop (mashup between space spaghetti and cyberpunk) and etc. And also play to Syndicate (90s), Shadowrun, System Shock, Deus Ex, Katana Zero, Transistor and so on. If you're not familiar with this, then it might be an interesting adventure.

BTW, the Shadowrun game universe is literally a fantasy set in a cyberpunk/sci-fi.