Well the universe' shapes werent procedurally generated, only the things inside. There were 3 blank templets for worlds those being "Forest", the absolutly masive one, "Islands" A bunch of islands connected via land briges, and "bridges" the one with real islands connected by bridges. Then there are spawn points that will randomly generate a structor. If you would want, I could get far more indepth with how the universe generation works.
When it comes to enemy's running you down from off screen, I definitely made the enemy detection a bit to unfair for how close the camera is to the player, I should have moved the camera out so you can't agro enemies while they are off screen. And I'm gald you liked the death's door mechanic, I was uncertain on how that part of the game would be received.
Yeah unfortuntly making art for the structors was one of the parts I left for last. While I did work on it durring the game to make sure I had something I never really spent the time I told myself I would at the end of the game jam to make more assets. Fun fact, if I had ever made trees, the colors of the leaves would have been randomized like the grass.