You guys need to understand the 15+ rule a tad better. To clarify, the rule is there so that when people under that age join and decide to squeek on the microphone, they'll immediately get kicked out (it's made easier for those in control of the server). On the other hand, if you're 13 and you sound like you're 25 then I suppose you should be okay joining in. I mean, Rawrplus is not going to check your age as it's almost impossible unless he knows you well and so on. Join the server, populate it but if you sound like a hyped 10 year old screaming and crying every time in the microphone, well, don't join.
Wanted to make this clear for all you of you GMOD lovers (underage).
