Laptop closed but with an external monitor?

My laptop screen is broken and I have an external monitor now. My question is when I set it to not switch to energy-saving mode when it is closed and I play online games while the laptop is closed, what can happen? Or rather leave the lid up

Start> Control Panel> Power Options. Then on the left click on "Select what should happen when you close the computer" and under "When you close" simply select "Battery" & "Mains operation" (or just "Mains operation" - depending on how you would like it) then "do nothing".

In the closed state it shouldn't be a problem to gamble, as long as no ventilation slots or something are covered.

When it is closed and I want to go into energy-saving mode and wake up the laptop with the mouse, nothing has to open the lid then it works again

Therefore you have to change the settings as I described above. Then the computer stays on even if you close it.