I feel like arena had been forgotten but it was a peak game
This that could be added are paint wraps like patterns on the guns
A level system letting you get arena styled cosmetics and wraps for guns
Later updates could be different maps
And and a weekly leaderboard
Features that could help people have a fair experience is if you add a moderate system by making it if someone doesn't move for a while in the safezone or just AFKing
They could get a warning
Rewards:
People should get a small sum of in game currency for having most Kills
And keeping the same limit a week by if they hit there limit they could get XP for there level pass
Everyone (who get more then 4 kills) should get a small xp sum because they tried
On update days there could be xp bonus days
Things that you could support are teams
Like the gorrila tag team the tree trotters (ttt