The bottom is an octagonal cage, but it lacks a base.
You can play games. But mixed martial arts is a fighting sport with certain risks, so be prepared:
A professional referee team and linesman must have corresponding professional knowledge to deal with unexpected situations at the scene.
Corresponding emergency plans, such as first aid for athletes, fire emergency and so on.
Professional competition rules, you can refer to UFC.
Cage fighting does not mean to compete in an octagonal cage. Strictly speaking, cage fighting can be carried out in cages, but UFC uses octagonal cages, and everyone has followed suit and used octagonal cages.