The game mercilessly pits you against a procession of boss characters,
usually on a single screen, and frequently unleashes «bullet hell» where avoiding incoming projectiles consumes as much as of your time as firing your own.
Electronic paper is unique: the fact that an e-ink sign will only use power when the image
on the
screen is changing means that e-paper is extremely energy efficient and will require only a fraction of the energy
usually necessary for a digital sign to work — so much so that it can run for months or years
on a
single battery charge.