Clarity
consistency
engagement
simplicity
utility
use features that retain the interest of
the intended player audience in the game
know the kind of fun the game must
create in the intended player audience
add minimum features that
meet the goal of the game
use one type of approach
in the game
provide flexibility for
future modifications

1)engagement

2)clarity , consistency , simplicity

3)consistency

4)clarity ,consistency ,simplicity

Explanation:

The answers of the four parts are as mentioned above.

If the game is engaging the interest of the interested players will be retained certainly.

If it is clear, consistent and simple, then you will definitely be able to retain the kind of fun the game will be creating in the intended player audiences.

If its consistent, then the game will certainly require one type of approach.

And if its clear, consistent and simple then the game will be providing the flexibility for the future modification.

Hence the above answer.