Cool
I've finished V.1 long ago, but I hadn't finished writing the reply until now
Here it goes:
So, back then when you released the level I got to the last screen of hard ending, but couldn't get it. I put the level off 'till I'm in the mood for it as I usually do with lunatic levels. After some time I returned to it and figured out mostly how to do the screen. In August 2011 I returned to it and finally finished it
I use the green buttons to test your endurance skills.
Sounds like RPG character's testing. In real life I'd call it 'willingness to perform repetitive boring and pointless actions', or 'masochism'.
BTW, I started The Descent To Hell, but only went on until I saw a green button challenge. Even seeing it made me not want to continue at that time. I don't mean to say green buttons are always bad, there may be good challenges with green button, like that last screen of hard ending.
Also, here's a rule of thumb: if you have a number of challenges on a screen, always put the hardest challenge first, always put the longest (time-wise) challenge last. Otherwise you synthetically increase play time and make the player feel cheated.