The player controls a ship in the centre of the screen, enemies approach from the top and bottom and the player is able to switch up and down to deal with the encroaching hoard.
Different enemies react differently when they reach the horizon, some sit on the horizon, some destroy sections of the horizon and some run up and down the horizon. The player is equipped with a dash attack where they can knock enemies off the horizon and smash them into other incoming enemies for a score bonus. Dashing an enemy of the line refills the dash metre allowing for ‘Dash chaining’, this is where the big points are scored.
The player is also able to jump (jumping upside down is an interesting new challenge) and is equipped with a bomb which wipes the screen of enemies as well as restoring the horizon.
"...It's also an exceptional sequel that not only improves on the original, but fully realizes the potential of its killer gimmick." A- Defunct games
“I went into this game with high hopes, and they were all met. I didn’t come across a single thing I didn’t like.” - 9/10 - The Insatiable Gamer
"...if you have the itch for some old-school arcade blast-em-up fun, Horizon Shift '81 is a great way to feed that craving." - 8/10 - The Sixth Axis
"This is one of the most charming takes on the shmup genre yet." - 8/10 - Cubed3
"...if you’re into shoot-em-ups and enjoy a good challenge, and particularly if you have a soft spot for retro games and indie games, the incredibly well-together package presented by “Horizon Shift ’81” is a compelling one..." - 8.2/10 - Infinite Frontiers