Think of attacker as a label for one position in a pair: two sides, and this is the one moving forward at the other. The word says nothing about the person themselves — only which end of the action they are at. Everything else, including whether it is or just a game, comes from where the sentence is set.
From the word’s history
The packet's Wiktionary etymology tree gives attack coming into English via French attaquer, from Italian attaccare; attacker is that verb plus the agent ending -er, which turns an action into the one doing it.
來源的字源樹顯示 attack 是經由法語的 attaquer（再往前是義大利語的 attaccare）進入英文的。attacker 就是這個動詞加上 -er，而 -er 把一個動作變成做這個動作的人——跟 teacher、writer 同一個做法。
packet Wiktionary etymology_text for attacker (kaikki:3f6f69a190036ae4:1026187793): Italian attaccare > French attaquer > English attack, plus agent -er.
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