Not Tyrian
As it stands now, it's mostly a tech demo, using sprites from Tyrian.
Basically, I figured out that, since most of Tyrian player and enemy sprites are 24 pixels wide, and most of the shots are 16 pixels wide, it should be possible to show a single enemy, plus the player, plus a single shot on a single scanline without flickering issues; so as long as as the enemies move at the same speed, are spawned at intervals that prevent them from overlapping their Y cooordinates and are restricted to only move horizontally after being spawned, and the same restrictions are applied to the shots, it should be possible to use them on a Sega Master System without resizing, only reducing the color count. This is an experiment to test how it would look like.
Originally made for the SMS Power! devkitSMS Coding Competition 2016, then further expanded for the SMS Power! Coding Competition 2020.