Aren't you going home yet?→まだ帰らないの？
yetは「まだ」という意味です。
You are still here?→まだいたの？
「あれ？まだいたの！？」という感じで、驚いたとき等に使える表現です。
例：Oh, you are still here? I thought you went back home! あれ？まだいたの？家に帰ったと思った！
Why are you still here?→なんでまだいるの？
「なんでまだいるのよー！」と比較的強く問いただしたいときに使える表現です。
例：Why are you still here? You need to have a break!! なんでまだいるの？休憩が必要よ！
This is an informal way to ask a coworker why they're still at the office and when they plan on going home. They will probably answer by explaining why they are still at the office. I hope that this helps :)
"You're still here?" is a friendly, casual way to ask someone if they are still working. In English "Burning the midnight oil" is a common phrase that means working late into the night. In the case of the second question, you are asking if they are staying late to work.
The third sentence, "You're sticking around?" is another casual way to ask a coworker if they are going to stay late at work.
"You're still here?"（まだいるの）は、まだ仕事を続けるのか尋ねるフレンドリーでカジュアルな表現です。
"Burning the midnight oil" は「夜遅くまで働く」という意味のよく使われるフレーズです。ここでは（二つ目の文では）、遅くまで残って仕事をするのか尋ねています。
三つ目の文 "You're sticking around?" これも、遅くまで残って仕事をするつもりか尋ねるカジュアルな表現です。
These are all appropriate ways of asking your colleague whether they are going home yet,especially if you have an existing casual relationship with them.If this is the case then there is no need to use formal language.For example :
-Heading home soon?
-When are you planning to call it a day?
*To " call it a day " means to stop doing what you are busy with,especially work,to go home and relax.
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これらは、特に仲の良い同僚にもう家に帰るか尋ねる適切な言い方です。仲の良い同僚にはフォーマルな言葉を使う必要はありません。
例えば：
-Heading home soon?（もう家に帰りますか）
-When are you planning to call it a day?（何時に終わる予定ですか）
"call it a day" は「〔仕事などを〕終わりにする」「家に帰ってリラックスする」という意味です。
Are you still here?
This is simple and very casual.
You not on your way yet?
When are you planning to head off?
I would use these examples when I am very comfortable with the person I'm talking too.
Are you still here?（まだ帰らないんですか）
シンプルで非常にカジュアルな言い方です。
You not on your way yet?（まだ帰らないんですか）
When are you planning to head off?（何時に帰る予定ですか）
これらは打ち解けた相手に使うことができます。
"Overtime" is used to indicate that more time than required is being spent at work. If the person is staying beyond the usual work schedule, this indicates that he/she may be making up time or working overtime.
It is typical to use the term "take off" in place of leaving. It is a more informal way to ask someone what time he/she plans to finish up and go.
"Heading out" is an expression meaning on your way out or leaving and is short for "heading out the door."
"Overtime" は残業をすることをいいます。もしその人が規定時間を過ぎて職場に残っているなら、残業をしている可能性があります。
"Leave" の代わりに "take off" というフレーズがよく使われます。これは何時に仕事を終えて帰るつもりか尋ねるインフォーマルな言い方です。
"Heading out" は「出ていく」「出発する」という意味の表現です。これは "Heading out the door" を短縮したものです。
Using "going home" or "heading home" can be used in the same way to say that you or someone is leaving to go to their home.
Example: "It's time to head home. It's getting late."
「家に帰る」と言う場合、"going home" と "heading home" は同じように使うことができます。
例：
"It's time to head home. It's getting late."
（もう遅いから帰らないと）
日本 
アメリカ合衆国 
南アフリカ 
イギリス 
