It is hard to judge the design when you have things like:

(The room, computer and character will be replaced! This room is temporary.)

One large improvement you could make to Gamedevtycoon would be to not hide why each game got the rates it did. For Example: Why did a simulation game about racing get a 9 in one area, but a 2 in another. Was it because there was a large demand for great graphics?

I like your graphical style, perhaps don't change it too much?

It's simple and easy on the eye and reminds me of 'crossy road'.

Not sure what you mean by

Google's material design

I've no problem with Crossy Road style graphics (and not sure why Brain's comment is downvoted) but considering these will likely be rather static probably with no 3D involvement at all, it doesn't fit the purpose of using such design.

Other than that there isn't much to ask or tell from such input imo, Game Dev Tycoon was a good game beside lacking competing AI and repetitive gameplay, if you didn't yet it will be a better idea to ensure having a GDDish document rather than just diving in.

As design language , I always prefer Modern UI over Material Design :)

And room seems fine to me, it's a style I am fond of.