A Mystery Manila Online Mini Game

They gave Pandora a box.

Prometheus begged her not to open it. She opened it. Every evil to which human flesh is heir came out of it.
The last thing to come out of the box was hope. It flew away

When you get the answer to the riddle, type in 'games.mysterymanila.com/mysterymessage/[answertotheriddle].html' on your browser to proceed.

�It cannot be seen, cannot be felt,
Cannot be heard, cannot be smelt.
It lies behind stars and under hills,
And empty holes it fills.
It comes first and follows after,�
Ends life, kills laughter�