There's certainly already Unity projects on the web in the space Flash used to occupy.
Also, HTML5's CANVAS tag, and modern web platform tools like WebGL, mean that you can do most of what Flash games did directly in HTML5 and JS. There's a growing number of 2D and 3D game libraries written entirely in JS or TS.
The biggest missing piece that made Flash so ubiquitous for early web games is the authoring experience. Unity is a lot more complicated than the Flash designer was. I've seen several game editors for HTML+JS libraries, but also nothing quite similar to how easy Flash was for early web designers. The codebase that inherits and succeeds the original Flash IDE lives on in a new name (Adobe Animate) and can directly target HTML+JS instead of Flash, but is a part of Adobe Creative Cloud and so too expensive for many of the hobbyist designers that made early web games what they were back when the DRM for the Flash IDE was a lot easier to crack than a cloud subscription.
Also, HTML5's CANVAS tag, and modern web platform tools like WebGL, mean that you can do most of what Flash games did directly in HTML5 and JS. There's a growing number of 2D and 3D game libraries written entirely in JS or TS.
The biggest missing piece that made Flash so ubiquitous for early web games is the authoring experience. Unity is a lot more complicated than the Flash designer was. I've seen several game editors for HTML+JS libraries, but also nothing quite similar to how easy Flash was for early web designers. The codebase that inherits and succeeds the original Flash IDE lives on in a new name (Adobe Animate) and can directly target HTML+JS instead of Flash, but is a part of Adobe Creative Cloud and so too expensive for many of the hobbyist designers that made early web games what they were back when the DRM for the Flash IDE was a lot easier to crack than a cloud subscription.