I've been spoiled by hardware controls, growing up with things like the GBA, Nintendo DS, and the HTC Dream / G1. The DS was a haven for homebrew and made a nice PDA before smartphones came around. My first cellphone was a used HTC Dream, with a well laid out keyboard that solidly flicked open, physical button on front, and a trackball that was fantastic for RDP/VNC.
This idea started in 2014, playing emulators in the break room at work. By that time I had a newer phone - touchscreen only with a few capacitive buttons on the front. I hated it. I couldn't touch type, couldn't use terminal worth a damn, couldn't easily control a mouse over VNC, and couldn't play action games.
The straw that broke the camel's back was "Prinny: Can I Really Be the Hero?" - I couldn't beat a boss because my fingers kept missing the intangible touchscreen controls. So I started mocking up a controller that would work with my phone.
I brainstormed and sat on it for white a while. In 2017 I started working on physical versions. I made one test with an Arduino and HC-05 bluetooth module, and then went to the nrf51822 SoC bluetooth module. Progress halted for most of 2018 while I dealt with life stuff.
Now it's 2019. Phone UIs and mobile game design have gotten better but playing action games is still putrid. I'm back, full force, ready to slam out a design in time for the Flexible PCB Contest.