A few questions about articles

I wanna try to make one or two articles but there are some things that aren't clear to me. I'm sorry if there was a place I was supposed to look t to clear up these doubts but I didn't know how to find it. I hope I can get some answers here. First of all, can I make articles about games that aren't in gamehag? And secondly, can I link outside resources (for the purpose of being helpful to knowing more details without making the article longer that it should be) or are links strictly forbidden? Thanks in advance, and if this gets taken down I'll understand that too.