Flickering lantern-light effects added to the Undertomb.

"Undertomb 2"
Section 1 - Procedure
Brightness is a kind of value. The brightnesses are guttering, weak, radiant and blazing.
A brightness can be adequate or inadequate. A brightness is usually adequate. Guttering is inadequate.
Temperature is a kind of value. 100C specifies a temperature.
A brightness has a temperature. The temperature of a brightness is usually 700C. The temperature of blazing is 1400C. The temperature of radiant is 1100C.
A dead end is a kind of room with printed name "Dead End" and description "This is a dead end, where crags in the uneven rock are caught by the [brightness of the lantern] flame you hold aloft. Despite [river sound] there is no sign of the stream." A dead end is usually dark.
A dead end has some text called river sound. The river sound of a dead end is usually "a faint whispering of running water".
Section 2 - Scenario
The Undertomb is a dark room. "From this dim cross-groined room, exits depart east, south, and northwest."
East is a dead end. South is a dead end with printed name "Collapsed Dead End".
Northwest is a dead end called the Tortuous Alcove. The Tortuous Alcove has river sound "a gurgle of running water".
The player carries a book. The description of the book is "[if the brightness of the lantern is adequate]Many secrets are now yours.[otherwise]No, the print's too tiny by this awful light."
In the Undertomb is a lantern. It is lit. The lantern has a brightness. The lantern is blazing. The description of the lantern is "The lantern shines with a flame at [temperature of the brightness of the lantern]."
After waiting in the Tortuous Alcove when the brightness of the lantern is not guttering:
   now the lantern is the brightness before the brightness of the lantern;
   say "You wait so long that your lantern dims a bit."
Test me with "east / west / get lantern / east / west / south / north / northwest / read book / x lantern / z / x lantern / read book / look / z / x lantern / read book / look / z / x lantern / read book / look".
Test me with "east / west / get lantern / east / west / south / north / northwest / read book / x lantern / z / x lantern / read book / look / z / x lantern / read book / look / z / x lantern / read book / look".
Undertomb
From this dim cross-groined room, exits depart east, south, and northwest.

You can see a lantern (providing light) here.

>(Testing.)

>[1] east

Darkness
It is pitch dark, and you can't see a thing.

>[2] west

Undertomb
From this dim cross-groined room, exits depart east, south, and northwest.

You can see a lantern (providing light) here.

>[3] get lantern
Taken.

>[4] east

Dead End
This is a dead end, where crags in the uneven rock are caught by the blazing flame you hold aloft. Despite a faint whispering of running water there is no sign of the stream.

>[5] west

Undertomb
From this dim cross-groined room, exits depart east, south, and northwest.

>[6] south

Collapsed Dead End
This is a dead end, where crags in the uneven rock are caught by the blazing flame you hold aloft. Despite a faint whispering of running water there is no sign of the stream.

>[7] north

Undertomb
From this dim cross-groined room, exits depart east, south, and northwest.

>[8] northwest

Dead End
This is a dead end, where crags in the uneven rock are caught by the blazing flame you hold aloft. Despite a gurgle of running water there is no sign of the stream.

>[9] read book
Many secrets are now yours.

>[10] x lantern
The lantern shines with a flame at 1400C.

>[11] z
You wait so long that your lantern dims a bit.

>[12] x lantern
The lantern shines with a flame at 1100C.

>[13] read book
Many secrets are now yours.

>[14] look
Dead End
This is a dead end, where crags in the uneven rock are caught by the radiant flame you hold aloft. Despite a gurgle of running water there is no sign of the stream.

>[15] z
You wait so long that your lantern dims a bit.

>[16] x lantern
The lantern shines with a flame at 700C.

>[17] read book
Many secrets are now yours.

>[18] look
Dead End
This is a dead end, where crags in the uneven rock are caught by the weak flame you hold aloft. Despite a gurgle of running water there is no sign of the stream.

>[19] z
You wait so long that your lantern dims a bit.

>[20] x lantern
The lantern shines with a flame at 700C.

>[21] read book
No, the print's too tiny by this awful light.

>[22] look
Dead End
This is a dead end, where crags in the uneven rock are caught by the guttering flame you hold aloft. Despite a gurgle of running water there is no sign of the stream.