

Winetricks -> Install an aplication. -> Click "Cancel". -> Run an arbitrary executable (.exe/.msi/.msu) -> Run a downloaded version of "K-Lite Codec" from <codecguide.com>
FMVs will create a new window titled "ActiveMovie Window". FMV will not play unless main game window "Moero Chronicle" has focus. FMV window "ActiveMovie Window" will be behind main game window "Moero Chronicle" by default. This occurs in both Fullscreen and Windowed mode.
Having the correct codec installed in wine will give the FMVs video. I don't know which specific codec is required but know from my Windows days that K-Lite basically covers everything.
You then use Alt+Tab to focus on the FMV window. Right click over the title and select "Always on Top". Finally Alt+Tab to set focus back to the game window. This can be done with a mouse, but the user runs the risk of miscliking on the game window which is the "skip cutscene" command. This can be done in both Windowed and Fullscreen mode.

While the game fully works, an average Joe would open the game, see a black screen and think "game is broken". Cutscenes need to be fixed.
Video cutscenes do not work well. Basically, the following happens:
- The game wants to play a video cutscene. (example: The Opening)
- The main game window remains black, but another/separate window is open (and gains focus) just to play the cutscene video.
- Since the main game window lost focus, the cutscene will pause until you click back into the main game. (the game thinks you alt-tabbed)
To watch cutscenes: you have to right-click on the 2nd window (where the cutscene is played) and click "Keep Above Other Windows", then click back onto the main game. The cutscene will now play as if it were a video player above the main game. This won't work in fullscreen (fullscreen takes precedence over an always-on-top window). If you're in fullscreen (or Steam Deck), either just skip the cutscenes and watch them on YT, or switch to windowed mode.
It's not a big deal since 99% of dialog happens as in-game dialog, rather than in a video cutscene. (The rest of the game works fine.)

The first launch can take about a minute, so be patient. the game will probably close after that. Relaunch the game, and it will be good to go from there onwards.
Using GE-Proton8-4 (which includes a new protonfix) the game is now working correctly, including cutscenes.
The first launch can take about a minute, so be patient.
All videos missing
4.11-13 is the only Proton version that could show me the game menu (after clicking a couple of times to get through the missing opening video)

Unfortunately not playable. Couldn't find any way to get to the main menu.
Black screens instead of videos
Intro videos can be skipped with a click, but I can't get past the black screen after starting a new game, even with MF-install.

Game does not play videos, and probably _never_ will
The in-game videos are encoded using the ASF format, present in a lot of games with non-working cutscenes (Nioh 2 for example). I tried mf-plat, xact+klite mega codec pack with other tweaks, Proton-GE, none of them work.
As cutscenes do not work I tried installing xact, wmp11 and the media foundation script. I also tried the glorious eggroll's proton fork but that way the game doesn't even open. Nothing actually fixed the videos.
No videos run, which is pretty important as this visual novel shows some plot points in video format.
The gameplay works fine but I can't think anyone would play this for anything other than the visual novel part, and that lacks without the video cutscenes.

It works, but you have to click in the beginning, otherwise it will be stuck in a black screen

Borked as most of the IFI games.

Doesn't run. Log: SteamAPI_Init() OK.
SteamAPI_RestartAppIfNecessary() OK.
St_Init() OK.
-- Moero Chronicle (build:1.0.15) -- -- MASTER 20190824164756 -- -- S T A R T --
libWinIniLoad finished libwinCheckMaxResolution finished libWinFindResolutionIndex = 7 libWinGetResolution finished GetLibWinWork finished libWinScreenSizeCalc fnished libWinSetPause: Off InfoLog: 0:1(10): error: GLSL 3.30 is not supported. Supported versions are: 1.10, 1.20, 1.30, 1.00 ES, 3.00 ES, 3.10 ES, and 3.20 ES

xbox 360 controller acting weird moving on it in the menus

I've been playing the game for 5 hours and it runs perfectly. No glitches, frame stuttering, or weird artifacts. Just make sure that when you first load the game and the screen is black, click a few times with your mouse to get it to start. I'm not sure if this is a quirk unique to Proton or if this also happens on Windows.