A super simple JavaScript based libretro frontend.
A running demo is available at https://matthewbauer.us/gametime-player/. There's also a Chrome App (built from the chrome branch) available at https://chrome.google.com/webstore/detail/gpemu/jhficiigpnhhaojldmanflihieepanbb.
The easiest way requires Node and Git.
git clone https://github.com/matthewbauer/gametime-player.git
cd gametime-player
npm install
npm start
Then navigate to localhost:8080 in your browser (Chrome, Safari, Opera, Firefox all work).