( I can not speak much English I hope you understand what I want to do )
I want to make the list of players online update the variables kills, deaths every 1.5 seconds.
I want the list of players update kills
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I can't honestly say that I have the answer off the top of my head but I think it would be good to look through these tutorials (My link is for the first in a series), as I believe they may give you a good starting place on developing your mechanic.
Best of luck!