The Hot Dark Room has no windows and no doors, nor vents or openings of any kind. You may not enter nor leave.
The air in The Hot Dark Room is still. Your breaths are heavy and labored.
The Hot Dark Room is as wide and long as it is tall. It is not large enough to stand, or even to sit upright.
The walls of The Hot Dark Room are thick, and padded so as to absorb sound. You can hear nothing beyond them.
And most importantly, the Hot Dark Room is dark. And it is hot.