When client-side anti-cheat scripts query Humanoid.WalkSpeed to check for speed hacks:

local oldIndex
oldIndex = hookmetamethod(game, '__index', function(self, key)
    -- If a game script checks our WalkSpeed, return the default 16
    if not checkcaller() and self:IsA('Humanoid') and key == 'WalkSpeed' then
        return 16
    end
    return oldIndex(self, key)
end)

Now your actual speed can be 100, but local sanity checks always read 16!

checkcaller() check is crucial so your own executor scripts can read the real WalkSpeed value.

Works on 90% of popular Roblox games. Bypasses client-side speed checks completely.