Rubicon is a trivia app for iPhone, free on the App Store. On anything else it runs in your browser, with nothing to install.
Get Rubicon: Trivia & Brain Duels from the App Store. It's free, with an optional Citizen subscription inside. You can also play in Safari, no download.
The Android app is coming. Until then, Rubicon works in Chrome or any other browser on your phone: open playrubicon.com and play, no download.
Play in your browser at playrubicon.com. Nothing to install.
It's the same account on phone, tablet and web. Sign in on any of them and your progress comes with you.