Need help on my arena (student lacking interest) T.T

Dear all,

I have a pool of student around 15 of them. Every week, I will ask them to play in an arena which i created for them. Eventually, they get bored of vs each other. Does anyone is there anyway that I can put in some computer/bot player to be in the arena and vs them? I really need some helps on this.... T.T

Thank you so much in advance...

Change the arena to atomic or some variant and see what happens.