Thanks for the feedback Franklin's Ghost!
I agree, the difficulty can be challenging so I'll be adding a difficulty adjustment in future iterations of the game.
The instruction screen duration is dependent on how long it takes the graphics to load in the background. As I add more graphics to the game the load time will be a little longer, giving the player more time to read. Even so, the controls are very standard for top-down shooters, but to make it easier, I plan on having a "casual" mode where the player won't even have to press space bar to fire.
Glad to hear you liked the voice narration! Thanks again for playing!