Now you're asking. I believe based on Google maps that it's Vithei BBQ Old Stadium. On khymer pub street.
But at your kids ages they may be at the upper limit of finding the room fun.
We were there in December with kids aged 6 and 7. We went to Pub Street for an early dinner then left fairly soon after dark. The kids had a great time - it was buzzy without being overwhelming. We went back without the kids about 8:30, and by then the vibe had turned - it was crowded, there were small girls selling cigarettes and begging with tear-filled eyes, and boisterous/drunken behaviour from tourists. So, my advice is go early evening or during the day (the day wasn't as exciting, but still okay). Have a great time!