the first part works fine, but then the last one just turns the fog neon:
repeat wait(5) game.Lighting.FogEnd = 250 game.Lighting.FogStart = 0 game.Lighting.FogColor = Color3.new(0,0,0) wait(5) game.Lighting.FogEnd = 1500 game.Lighting.FogStart = 250 game.Lighting.FogColor = Color3.new(255, 255, 255) until false
It is because you are using Color3.new() and not Color3.fromRGB().
Try:
FogColor = Color3.fromRGB(0,0,0) -- and FogColor = Color3.fromRGB(225,225,225)