Who was the game designed by?
is 和was 都是可以的,但是强调的内容不同?
Who was the game designed by?这个游戏（之前）被谁发明的?
Who is the game designed by?现在这个游戏是谁发明的?
2.When you have got enough points,a cloud will come down
用完成时态,首先一个原因是,得到足够的分数,发生在 come down之前,
然后是,前者是后者的一个原因,符合完成时态“过去的一个动作,对现在造成影响”的说法；