Bower: I couldn't find a Bower package for @Cycle/Core, @Cycle/DOM, do these libraries exist? I'm confused at why there is an NPM package in the first place since Cycle.js is front-end based (and NPM is specialized for back-end only).
ES5: Is it possible to use Cycle.js with Gulp/Typescript/ES5 (and not use Browserify/webpack)?
Everything Frederik said, plus here is a standalone Cycle.js example on codepen. You can see the links to the JavaScript files being loaded by clicking on Settings, then JavaScript. Here they are for convenience:
https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.7/rx.all.js
https://rawgit.com/cyclejs/cycle-core/master/dist/cycle.js
https://rawgit.com/cyclejs/cycle-dom/master/dist/cycle-dom.js
Full example is on codepen