This is why we need copyright expirations. Disney would most likely have sued with a cease and desist to remove it.
Does it use the likeness of old Disney properties? Yes... but it doesn't hurt their image. Doesn't take any profit away from them.
It's also not a cash grab like those crappy Winnie the Pooh slasher movies. This pays homage to the art style of the time.
The only thing they could have done differently was use something different than a mouse... like what Cuphead did. Studio MDHR came up with unique characters and it paid off for them by getting their own animated series and merchandising. I don't think Mouse P.I. for Hire will get the same type of deals, but time will tell.
Disney does not, nor did it ever, own the copyright to an entire state of animation. To my knowledge, it can't even be done. It'd be like trying to copyright a particular painting technique.
I doubt Disney would give a shit about this game unless it was explicitly using Disney ripoffs or actual Disney IP. Which it isn't.