Hold W while pressing the green flag to enter TUFFMODE - buffmode except stickmans killtimer is that of old buffmode, music box goes down faster, stickman and zowzer are less visible, night is longer, power is 15 and power generator is smaller. TLDR: Buff mode but it tests your patience and is super duper hard
The mode may seem completely impossible but at least your doors stay closed for less time and theirs no flashlight tuffmode is very consistent, once you know the loop and your mouse flicks are fast and precise enough, it becomes consistent. If you can get a minute in you can beat this mode if your will and patience are strong enough