The green door requires both characters, as stated in a yellow book from the first level.
* I still can't into proper "slideshow" cutscene/dialogue stuff so slowing down the animation of the cutscene is the least I can do.
* Maybe I could use an icon of their heads. I'd say the bigger issue is how it's not actually leaning to the border of the green but again, too ambitious for my first game.
* I've heard of Lost Vikings. Least I can do is make later levels handle the core gameplay better. The idea here was to press Z to attach the kid to the ladder after he swims high enough to reach it.
* The "surreal" visuals may or may not be intentional because my art skills are weak and when I imagine my characters/settings, they don't look like how they actually do in my stuff. After all, i still haven't added shaded to the characters in the cutscene.
But thanks for your and the others' comments.
I may still need to figure out things before adding new levels and content.