Been meaning to get to this, but May is probably going to be my worst month availability wise where weekends are concerned.

I've been meaning to try Tribes: Ascend for some time since you mentioned it so I wouldn't say no to that.

Age of Empires would be cool too, but it is a steep investment for people who might just be interested in playing together this month. If there are enough people on board I'd be down for it though assuming the timing works for me.