Sex talk is definitely NOT off limits during online gaming my friend.
As far as specific ettiquette I would say just use your head and be tactful about it. Different women are going to warm to sex talk at different times and in different ways.
My advice to you would be to follow the standards of online gaming: Build comfort by just having normal playful conversation, while at the same time building attraction through some negs and some cocky/funny attitude.
You should be able to read her IOIs and kind of instinctually know if sex talk would be welcomed by the specific girl at that time. If you can't get a read on her then give it a try man. The most important thing to remember when attempting any sort of escalation, is to NOT SWEAT IT if she doesn't go for it on the first try. If she shoots down the sex talk, seems put off, or disinterested...then just be patient. Go back to building comfort and try again later when you feel you've built things up
There's no better way to learn than to just give it a try. Some girls will be sending you naked pics and talking about how they're wet at the thought of you fucking them on the very first time you talk to them...while other girls can take days, weeks, months to get to that point. Just be flexible, patient, and do your thing
