So, recently, Dino Crisis 1 and 2 released on GOG.
Obviously, being a fan of the first one and the bundle with both games being cheap, I bought it.
But, by default, I was greeted with a "DirectDraw" error on launch, no matter the Proton version.
Turns out the solution is easy : the game needs to load a dll (ddraw.dll) from the game files, instead of the default one.
You need to tell Heroic that, which is done via going into the game configuration, "Advanced" tab, Variable.
Add a variable named "WINEDLLOVERRIDES" and put "ddraw=n,b" as its value. Then click the green "+" icon to actually have it saved.
That's it, just launch the game, be ready to reduce the volume a lot (the game launches with 3000% volume).