I'm not going to show up to game night
Why don't you want to play on game night?
It's boring just to stay at home and play board games.
I hope you already let people know that you're not going to show up. It'd be rude to be absent without telling them beforehand.
It's okay. They won't care anyway if I am there or not.
Since you made a commitment to be at game night every week, not letting people know that you will be absent is irresponsible. You don't have to go, but you do have to give someone a heads that you're not coming.