Seriously? Now what?

Okay, our loft upstairs is a constant thorn in my side. First of all, my kids are at a good age now where they are able to clean up after themselves and keep their rooms pretty clean. Cole is great at this, always has been. His room is always free of toys on the floor. Jacob needs to work at this. He's getting better but he likes to shove things in his closet which makes it very messy. Our loft is an extension of our family room upstairs. I love how big and open it makes everything seem. Lately though the kids have been using it as their personal toy space. They bring toys out from their rooms and play with them in the loft. It's gotten worse. I don't know what to do with it anymore. I have a toy box in there, but it doesn't get used. They build their legos in there and then they like to keep them up for awhile. It's not flowing well with the family room. What should I do about it? I'm thinking of maybe getting a room divider, but I would probably need more than one. Maybe some type of shelving? I'm wanting to get it organized as well as the den, but I'm trying to decide where to start. Here are some pictures of the loft. See how open it is, but it's such a mess. They even have legos on the air hockey table now. Oh boy. I'm not going to take pictures of the den cause it's worse. I love that I can close the door to the den to keep people out, but I can't do that with the loft cause it's just open.

See the air hockey table being used as a lego table now? Good grief!

It's just not meshing with the family room side at all.