my place is the hang out place too. I love it. Hope it continues.
I have three kids sometimes 4 at a time if not more...ages range fro 3-12. Mostly have 5, 6, 8. one boy and two girls. They come over daily, the 2 girls. I supervise them as though they are my kids. They respect my house rules as my son does. Same goes for outside. If kids are rough, you set some rules with the kids if they wish to play on your yard. If they can not follow it, they must go elsewhere. They need to respect your rules at your house, no differently then at their own.
if any child play rough house, i warn them...if you play that way, and get hurt, do not come running to me. Its a choice they make. Now i am always watching and listening. If i see something inappropriate or can cause harm, i have no problem speaking up or telling them to knock it off. I am over cautious in protecting my son or any child. I have a two story play structure anyone is welcome to play on. I have rules on that too. for EVERY one.
The girls and my son are not allowed to cross the street without adult supervision and same goes for them going to the kids house down the street. They are older and play in the street. Wont happen unless i am there keeping eye. I just watch....look out for cars and direct if needed to keep the youngins safe.
your yard and house rules should apply to everyone. if the hang out continues, go speak with their parents. Tell them they are always welcome over but must follow the rules to play safely at your yard. If they do not, they will not be welcome back. Let the parent know you are not responsible if anyone get's hurt...so player beware as they must make their own decision if they are of age. Youngins, different story. If you are okay supervising the youngest, then continue, if not....tell the parent if their child plays over here, they must be present or arrange a playdate so you can be available to supervise.
DO what you feel is right. again...its your house. your rules.