Well done, you’ve found the missing Ray Harryhausen movie! Reading through, I visualised this in 20th century stop motion rather than in recent cgi.
This is a death or glory mission as it reads, I guess the only way to use it in an ongoing campaign for visiting heroes is to give them some sort of escape mechanism to use if things go wildly wrong- it’s then up to the players to choose to use it and leave the city to its fate. They could take on some guilt effects or such in later games as a result.
So the question for the DM then becomes how do they get out.
Great set up, nice!