First of all: This is an amazing thing you've done here, I feel like I'm playing a proper sequel to Cave Story, I think Pixel adopt this officially when it's fully complete.
Second of all: This mod is in desperate need of a walkthrough/guide. A lot of times it's not really very straightforward as to what you're supposed to do next, and it makes the player (meaning me) constantly feel like I've missed something, or that I'm doing something wrong. I'm all for open exploration but some clearer in game clues as to what the heck I'm supposed to be doing would help loads. I mean, I tried to do Egg Corridor before going through the reservoir because I assumed that you could choose to do them in either order because Curly gives you the air tank and basically tells you to go to either one. So I make it all the way through the Egg Corridor (which is sadistic by the way), get the ID card, just to get blocked by the door AND the window. To make this worse, I then had to play through the level backwards just to correct my mistake. That was SO frustrating and could've been easily avoided if I'd been given a stronger nudge to the reservoir or if the door to the Egg Corridor had remained locked until I'd done the other stage.
Third of all: Just a couple of little bugs that I've found so far, and I'm sure you're aware of most of these. In the Sand Zone rest area, there's an experience capsule floating off to the side, out of the actual area of the room. I think this next one is just after coming out of The Labyrinth after riding Monster X (I may need to check this one again) but when you enter first cave again, there's a missing block in the roof just to the right of the entry door, which you can use to walk around the outside border of that map for a little bit until you become unable to move and start drowning without warning (again, sorry if I got the location of that completely wrong, but it's one of the cave areas that connects to the original). After defeating the first Genesis boss I went back and talked to Curly and she told me to talk to Misery. I talked to Misery (going through the puppy maze AGAIN, which made me want to drop my brain in a blender) and she literally just told me exactly what I had already been told. After making it all the way back to Curly (going through the puppy maze AGAIN) she still told me to go talk to Misery! So that was terrible. (EDIT) one more little thing, when you temporarily get the nemesis for the first Genesis boss level, during the dialogue in which you pick it up, you can still jump and shoot.
Lastly, and this is purely just a noobish question: I'm stuck on Oblivion: Erosion. Is it possible to fly past the death traps, or am I missing something else?