Re: Packedrat
I'm guessing that he's referring to the grenade eggs, since they open the one green door in the entire game. Unfortunately, I don't remember where it's found.
I must say, as much as I really like the game and its voracious content and smooth animations, it's confusing as all hell. There's not much logic at all to its progression, or in how the world links together. You can go super far into one area and then get stuck literally out of nowhere, and there are literally five different routes you can take just to get stuck at the same place. The maze where you need to micro'd by the blue flying cats is also awfully designed, as well as the desert area. There's even a symbol for a boss being at the top of that area, but that room is just empty with a pink/purple-ish background.
Once you've visited all of the areas (at least to my knowledge), the backtracking gets horrendously painful. When you get the rat transformation power, there has already been way too many places you can use it, and way too many of them being useless, that you've completely forgotten where even half of them are, and looking at the map is almost even more confusing than just running around aimlessly.
I really wish the game's maps were better designed and more logical. Castlevania and Super Metroid are both made like mazes, but they both have logical progression that to at least some extension lead you on the right path automatically. This game just doesn't... unfortunately.
Despite my issues with finding anything in this game or making sense of the map, I managed to find what I believe is all of the current upgrades: fire, electric, ice and grenade eggs, as well as the rat transformation. The debug menu speak of a bat and a micro transformation, but I'm at a loss as to find them and have defaulted to believing that they are simply not implemented yet. At least I've had a ton of fun with the bosses and the animations. Great vore game, and I look forward to playing the finished game. Almost as much as I dread attempting to navigate it.