I've long been fascinated by the intense role of path dependency in what technologies and art styles get really explored and mapped out in connection with computers, and I think Flash is a magnificent example of that in action.
Until Flash got really big, 2D vector art styles in games were really pretty underexplored. Not totally - there were games like Out of This World, say - but in general 2D games historically leaned very heavily on bitmapped art work. And that made sense, given the nature of the sprite hardware of arcades, home consoles, and some 8 and 16 bit home pcs (like the C64) in the 1980s and early 90s.
But that meant at the time that there never really developed a culture of 2D vector game art that was a magnet for super talented, competitive artists who really tried to push the space to its limits, see what was possible, drive a tool ecosystem, share techniques, etc. And of course you _did_ see all of those things happen around bitmaps and pixel art - the very best of 16 bit pixel art still does look really impressive.
Instead, most of the effort that went into 2d vector art at the time (at least this is my understanding) was more over in the land of business, where real time frame rates on cheap consumer hardware weren't a concern, and having crisp and clean graphic design and fonts that could scale up (especially when printed) were much more important.
And then GLQuake and 3dFX Tomb Raider and the Playstation 1 hit, and and something like vector art (in the form of polygon meshes) suddenly became ubiquitous in games - but all in the context of 3D rendering, 3D cameras, 3D worlds, and so on. And that did indeed become (and remains) a magnet for super talented artists to try to drive the state of the art forward, shared techniques, build tools, etc.
Along the way, the rise in graphics capabilities became more than enough to enable really interesting real time 2d vector art work in games, but there just wasn't a critical mass of interest in it (probably because the massive leaps in 3D rendering in the late 90s through the 2000s were sucking up all the attention, and 2D gameplay was at the time viewed as the past).
And all that remained true until the circumstances where Flash rose, which 1) ran on reasonably powerful PCs but 2) largely didn't use 3D hardware, and all this in 3) highly file size constrained environments (because of internet deployment), while 4) shipping a small runtime plug-in that evolved into a pretty good stripped down real-time combination of Illustrator and Photoshop, along with 5) an integrated authoring tool that was good for making 2d vector art - and all of this in the context of 6) really massive potential audience size because of web browser deployment.
All of those constraints and capabilities together were a really fertile space for 2d vector art in games to become a magnet for attention and talent and evolution, making it one of the major art styles in games today. Maybe that would have happened anyway, but Flash certainly played a major role in the world we actually live in.
**
Flash really left its mark as a stripped down, real time Adobe Illustrator, but its runtime (less so its authoring tools) was actually equally powerful as a stripped down real time Photoshop - something like what the Super Nintendo or Amiga could have conceivably evolved into had 3D acceleration never shown up, and if massive amounts of RAM and level-loading-time rendering and caching became a central rendering paradigm.
I was doing, I think, pretty striking indie work from that angle between 2010 and 2013, but I never quite found a way to turn it into anything and wasn't as good at shipping and networking as I needed to be (be honest with yourself when you need a business person or a producer, folks) ... so I'll dump some videos here instead, because why not.
So, the first approach I did was something like a Flash evolution of the parallax techniques used in Shadow of the Beast (and other 16 bit games):
Sideview Rendering Demo: https://www.youtube.com/watch?v=ybHJx-S3LWk
Incomplete Platformer: https://www.youtube.com/watch?v=MRUDYdfwvCI
And second approach was something like a Flash evolution of the techniques used in Sega's After Burner 2, Sega's arcade Rail Chase, Sega's Power Drift, or Sega's Galaxy Force 2:
Incomplete Racing Game: https://www.youtube.com/watch?v=mrL33EF-v0I
Cartoony Minecraft Demo: https://www.youtube.com/watch?v=5h1zzLOCAaQ
Unfinished FPS Wolf Horror Game: https://www.youtube.com/watch?v=k2WgC7OL8Aw
81k First Person Grass Demo: https://www.youtube.com/watch?v=rRsc0salnEs
All in file sizes I've updated some of these techniques to work with Canvas more recently. The parallax scrolling techniques in particular work quite well on phones and tablets with javascript and Canvas.