To sum up where we are so far and what has yet to be figured out... Now with pictures!
// spoilers
I am going to assume that you're able to figure out the house intro and chair puzzle on your own for this summary.
First, I'm gonna talk about the sav files. You can find your save file at C:\Users\<USER>\AppData\Local\CourageOW\Saved\SaveGames . When the game crashes at various points, it'll update the Courage.sav file so that next time you start the game, you'll be in the new location. If you open the sav files in a hex editor like HxD, most of the contents are pretty much identical except for an English string near the bottom (ex. "The Time" or "Was Good"). You can edit the string and load up the game to be loaded into the corresponding map.
The intro screen when you load a new save file tells us that there are 3 data missing scenes to find. That was our first goal. We have found all 3.
An interesting note about the sav files of the 3 data missing scenes is that before the usual sav phrase (which is always the same phrase as the map right before the data missing screen), all of them contain the strings "And Fair?" and "BeforeTheStorm". Sometimes the sav for one of the data missing scenes also contains the string "No". We do not currently know the purpose of the "BeforeTheStorm" string or if the "No" string is a bug or purposeful
The first data missing screen was found by Bryce Bucher. To find it, complete the house intro and chair puzzle as normal. Then go through the hidden wall (follow the bird sounds) and jump off the side. You will spawn in the house with no furniture. The sav phrase for this scene is "Was Good". If you wait around in the house, you'll eventually hear some Morse code. Otherwise, go upstairs, interact with the door, and then when you go back downstairs the grandfather clock will be in the middle of the room. Be sure to JUMP OVER THE RAILING into the room instead of just walking down the stairs. If you just walk down the stairs, the clock will chime 12 times and the game will crash. However, if you jump over the railing, the clock won't start chiming and you can interact with the door in the back of the house to get the first data missing screen.
The Morse code during this sequence translates to "Learn The Way Of The Old Wind". It is worth noting that the phrase "Old Wind" is pretty important. The game itself is called CourageOW (we think OW stands for Old Wind) and there is also a file in CourageOW/PortFiles/Data/Logs/..txt that says "She followed the rules He broke the rules The O██ W███ was all the way to the right". And we believe the censored words are Old Wind. I'll talk more about what we think Old Wind might mean later in the post. Side note: If you open the README file it says "When you find a dead end Just erase time", but we're pretty sure that just means that when your save is unusable (you found a data missing screen), delete your sav file.
The second and third data missing screens are both found by going to the end of the two hidden paths in the void room. To get to the void room, do the house intro and chair puzzle and then go to the end of the hidden wall path to interact with a hidden question mark. Then go north of the chairs to find a portrait of Muriel and interact with it. After the game crashes, you'll spawn in the void room. The sav phrase for this room is "The Time".
In this room, there are two invisible paths off the NW and SE of the start. As found by duckenheimer, if you run the background music through a spectrogram using a program like Spek, you'll get a map of the invisible paths. However, they're incredibly difficult to follow with lots of turns and long paths in the dark. TheBeardeDude found that you can instead use a program called Reshade to see the invisible paths by shading the display depth.
Following the SE path, you'll end up at a light that, when interacted with, will teleport you to a pitch black room with a locked camera. If you walk forward, you'll find like a cardboard cutout of the front of a house. Note this house because we'll be talking about it again during the OldWind discussion later. and behind it is a portrait of Robert Wheeler. Interacting with that will crash your game and update your sav file with the string "I Don't". You'll spawn in the house, but it's very dark. Going upstairs will start a cutscene of a humanoid creature moving towards you (the name for this creature in the files is RealWheeler). Then you get the next data missing screen.
Following the NW path, you'll end up at the chair under the spotlight. Interacting with it will crash your game and update your sav file with the string "When the World". You'll spawn in the house with a bunch of coins scattered about. Collecting some of them will slow the music and some HUD with Muriel as player 2 will appear. Then, after collecting all the coins, her portrait will darken and you'll get the last data missing screen.
If you brighten the 3 data missing screens, there are hidden phrases that says "Father wasn't home", "Mr Wheeler was there to greet me", and "It was her Eleonor". We do not currently know the significance of these phrases.
After finding the 3 data missing screens, we had the following sav phrases: "The Time", "When The World", "Was Good", "I Don't" as well as the other strings that appeared in the sav files "And Fair?", "BeforeTheStorm", and possibly "No". From attempts to make a full phrase using these, it was found that you can use the phrase "Remember" and it will load the game as if it were a new save. NeitherNathan mentioned in a discord message that the first sav phrase in the full phrase wasn't appearing in the sav files due to a bug. Currently a new sav file doesn't contain any phrase. Because of this, we believe that the "Remember" phrase is supposed to relate to the new save scene. Then, using a program called Cheat Engine to search through the running game's memory, it was found that the last sav phrase is "Do You". We do not currently know the intended solution to find the "Do You" sav phrase. So, it appears the full sav phrase may be "Remember The Time When The World Was Good And Fair? I Don't Do You". The reason for "Do You" being at the end instead of the beginning of the phrase is due to the ordering of the phrases in the memory, but I feel it may make more sense for it to be at the beginning due to the punctuation. However We do not currently know what the significance of the full sav phrase is.
Editing your sav file to use the "Do You" phrase spawns you in a greybox version of the house. The only thing you can do is go into the computer room and interact with the computer over and over. We do not currently know if there is anything else to do in this scene.
And finally, let's talk about OldWind. This phrase appears a lot throughout the game and it seems to be a central pillar of the ARG. If you extract the .pak files of the game using Unreal Engine's UnrealPak.exe and open them with UE Viewer, you'll see that the following things have filenames relating to OldWind: The design under the chair puzzle, the coins that have the same design, the darkened Muriel P2 UI, and the cardboard cutout house model. If you look at the chair puzzle design, you'll notice that you can use it to (kind of) spell out OLDWIND. We believe that there is a way to interact with the chair puzzle in such a way to input the letters OLDWIND, but have not yet been successful. Since there are missing chairs and it is unclear which chair to start each letter with, we haven't figured this one out yet. My theory is that successfully inputting OLDWIND into the chair puzzle will give us the "Do You" sav legitimately. Note that having to figure out how to input these letters would fit nicely with the Morse code that said "Learn The Way Of The Old Wind".
As for the other two files related to OldWind We do not currently know what the darkened Muriel UI nor the house have to do with OldWind. The house may be related to the clue that says "The O██ W███ was all the way to the right" since in order to get to the house, you need to go all the way down the right path in the void.
And that's about all we know at this point. NeitherNathan has recently posted on Twitter that there will be an update to the "port", so I'll be sure to revisit this once that comes out. Thanks to NeitherNathan and Chicogames for the great ARG so far! Looking forward to more.