Those are just common words and terms for game modes and objects. Most of them are used in other places or the real world.
Biorifles appear in games like Firefall and others as well. canons are real and used by militaries, but they are actual canons. Capture the flag was first introduced in the videogame “Bannercatch” in 1984; it was an educational game based on the real game capture the flag, which has existed for so long, no one remembers where it came from.
As a rule, avoid using anything that you think may cause legal trouble down the line, but also be sure that the idea/term is trademarked/copyrighted.