Just enough story to motivate me to keep going (Knowing why I'm here doing this means a lot to me) and steering the ship feels so great I just couldn't stop. The first three bosses weren't really great, in that they were too samey and not challenging, but Epsilon and Theta are really good. The real bosses are the walls in many ways, as enemy fire didn't kill me once, the huge spikes thing killed me once, and 99 deaths were by walls crashing on me. Epsilon's speed made me respec (very thankful for allowing this btw) into speed to not lose to the walls, and Theta's healing made me change strategies and be more aggro in the fight to outdamage the healing. Such balancing to make me engage with the mechanics and change my gameplay makes the game pretty good, only wish the first three bosses (mostly second and third, since the first one is your tutorial and should be that simple) had more of that to make the experience rewarding from start to finish.
Also, this feels very much like the prologue to a larger story, in that you get to play this character to meet the world, and then when he is killed, control transfers to the person who called him a few times and you get to continue investigating this world, the Void and the company. Using a jam to produce a doomed prologue setpiece is actually genius work, really activated my almonds.