My older cat has assumed this as her own lounge set, using all levels, the house and bats at toys.  This is wonderful as she had become withdrawn when I adopted an abandoned stray who is very playful with floor toys, flying feathered toys, but will not acknowledge the new cat furniture.  It has put much needed movement into my older cats life as she moves from level to level and bats at the fluff balls.  I feel it's instability would not support two very playful 12 lb cats.  I am constantly tightening bolts, but always happy to see my older cat surveying the outdoors and the living room from the top perch.  I love the many scratch posts as does the cat.  I'm glad I got it for her sake.  This would be a great piece for 2, 3 kittens to romp on.