Can we ask questions about specific games for Ubuntu on AskUbuntu, or should we ask them on Arqade instead? I would like to ask how to get a game running but I don't know which site I should put it on.
Making software run in Ubuntu is totally on topic for the site. So installing and making a game run are fine.
Questions about playing the game should be in arqade.
If the question is ubuntu related, Eg playing games in ubuntu, You can post in askubuntu, for other game related questions can be ask in arqade
I have asked only one question on this site. Its resolution was an ubuntu-specific configuration that I found in an Ubuntu bug report. It's a 3 times notable question with now 2500 views. It is of very general interest to the community. It was and is still closed as off-topic.
So apparently, here as elsewhere on stack exchange sites, one can always ask.
Nothing prevented me from asking that question.