Hard to tell in general, but i personally like the b&w theme. ( I think colore could be cool too) greetings Os
There is not, in general, a most appealing solution. It depends on the context. If you want to create a creepy game(like in the video), the B&W style is pretty interesting, but that style used in a FPS could be annoying and frustrating. I hope that was helpful!
My opinion is grey scale is good for simpler games, but as they get more complex, colour gives you an extra dimension which can be very useful. Saying that, if you have an idea try experimenting, there's always a chance it could be a game changer.
It really depends on how you use colors/graphics in general. For example : Normally Role playing games use high detailed graphics to make the player feel that he/she is in another world, some games use very few colors to create an effect of simplicity and some games even use colors as a part of the mechanic or the gameplay. The video that you linked did not only emphasized a black and white style but more of a "Pencil and Paper/sketch style".