Arc Dark is an Atom theme heavily inspired by the Arc Theme for Gnome.

The font used in the screenshot is Fira Mono.

The "Combo" Score System seen on the top right corner is the 'activate-power-mode' plugin (not included in this theme).

The syntax highlight is Monokai. (Not included in this theme.)

Install the theme via Atom by going to Preferences/Settings > Install and search for Atom Arc Dark UI (or atom-arc-dark-ui, make sure you're searching under 'Themes'), or install through CLI:

$ apm install atom-arc-dark-ui