#5 missing red key in level 10

[Ricardo Mones]

This comes from Debian bug #774270, from original submitter's description:

• Problem description:
  In level 10 a red key is missing to unlock the doors.
• What exactly did you do (or not do) that was effective (or ineffective)?
  Starting the game played until I reached level 10, killed all monsters,
  collected everything, discovered the whole area and found no red key but
  the red door needs it to go through.
• What was the outcome of this action?
  No red key in level 10 at all.
• What outcome did you expect instead?
  Find a red key to exit.

Thanks in advance,

[Giuseppe D'Aqui']

In level 10 the red key is at the end of the second vertical
passageway (see the screenshot attached). If you are not careful, the
second bomb will destroy it.

AFAIK the levels are all playable until level 22, the last one.