BounceJS.com has a nice UI with building blocks! And it transpiles / exports to CSS3 animations. The reason why I don't like using CSS3 for web animations, is that it requires modern browsers (although that's not a big problem anymore), but far more importantly it doesn't allow quick "scene reordering". Suppose, after coding a bunch of animations, you decide (or your hiring client decides) to move "animation part 5" to "part 3" and "part 2" to "part 4". Then you're back to square one!
However, using GSAP (and my gsaw-js therefore as well) you can "wrap" animation scenes in multiple timelines. And also it allow for re-using pre-built animation components. The problem with GSAP however, is that it's not exactly JS-beginner-friendly... And neither is "regular" CSS3 animation coding, why would otherwise Animate.css (and family & friends) be so successful?
gsaw-js is intended as a pre-fab "Add Water" animation lib. You only add an HTML class to the element you want to animate, et voila!
BTW: there's plenty more room for DOM / SVG / Canvas animations than just in games:
E.g. advertizing banners, web apps, call-to-action buttons... Just watch where I'm steering gsaw-js to! I'm hoping to commit v.0.2 later today!