[noduerme]

I'm surprised no one has mentioned vector-based animation, which was a primary tool in Flash. AFAIK there's no SVG solution that comes close in performance or flexibility to keyframe- or programmatically animating complex vector graphics (with user interaction!) the way you could in Flash.

[ChrisRR]

The stickman fighting animations were a classic of the flash days.

[soulofmischief]

For the uninitiated: https://www.newgrounds.com/collection/xiaoxiao.html