Exploring a terminal-like user interface in a mobile app

I'd like to introduce Trtl, a mobile app I'm working on with a terminal-like UI.

I don't see many mobile apps on HN but this one has a twist that I thought might be interesting to the HN community.

I recently sat down to write myself an app to record business trips in my personal vehicle and the simple use-case was an excellent opportunity to explore an old thought that a terminal interface could be a good fit for mobile.

There's a concept in the UX world loosely called "Reachability" which refers to how much of the screen the user can comfortably reach with their thumb. The idea behind it being that frequently used elements should be located within that convenience zone. A terminal-like interface, with it's keyboard-first interactive model, is very compatible with this.

Further, our fingers are also the mouse in the mobile context so mouse-centric design patterns like buttons can still be useful. One example of this in Trtl is the custom odometer entry control. It uses the keyboard for entry but you can also change the currently selected digit by tapping the UI element. The actions presented in the command lines are also tappable!

It's definitely not perfect. There are some notable UX issues to iron out, touch target sizes, discoverability, etc. Still though, I'm personally surprised and impressed by how well a terminal-like concept works in a mobile app.

Thanks for looking!