Section A - Light Solution
To decide whether the vent is noticable:
[if the Clean-Room is light-filled:
repeat with the item running through visible things in the Closet:
if the item is the player, next;
if the item is lit, no;
yes;
no.]
if there is a lit thing in the oven, yes;
no.
To solve the vent:
if the vent is unsolved:
now the vent is solved;
award points for "finding a backdoor into the Clean Room";
move the vent to the Disused Closet.
Every turn when the vent is unsolved (this is the discover the vent rule):
if the vent is noticable and the player is in the Disused Closet:
say "A strange light shines from an inconspicuous metal grating near the floor.";
solve the vent.
Rule for writing a paragraph about the small vent:
if the vent is noticable:
say "A strange light shines from an inconspicuous metal grating near the floor.";
otherwise:
say "An inconspicuous metal grating is set into the wall near the floor.";