Say "oops" when *you* mess up. Say "good game" when *you* lose, and say it back to people who say it when you win. Take the time to say "hello" at the start. If they do something cool, say "nice". You're not playing alone.
You are playing against people, all kinds of people.
Saying oops when THEY make an error, or you counter a spell, or you kill a creature, is rude. It's gloating. Saying "good game" when you think you've won isn't good sportsmanship. You're not playing alone.
Nobody wants to hear you congratulate yourself. People are playing to both win AND enjoy the game. There's no reason to be a jerk about it.
I think we've all been isolated from strangers for long enough that people are starting to forget how they would treat others in person. Would you say the thing to someone directly, without any smile or laugh or friendliness in your tone? No? Then don't say it in text that has no nuance (like on this game).
Be kind. Save the cruelty for games with chat among friends or people who know you're screwing around. In that environment it's fine.
![](https://s2.save4k.ru/pic/Obdv8kXvM1E/mqdefault.jpg)