"The game is about to start!"

Translation: 比赛快要开始了！

[ashaman5]

really, is the "le" is necessary here? particularly if it hasn't even started yet.

[looli23]

The 了 here is a must. The sentence is not proper without it.

The actual phrase is 要...了，or 快要...了, which indicates that something is about to happen.

In short, 了 here does not mean "something done", but rather a change of situation/state.
Please refer to the explanation here：https://resources.allsetlearning.com/chinese/grammar/Expressing_%22about_to_happen%22_with_%22le%22

[NelsonColin]

I was marked correct without the "le". It would not have occurred to me to use it either