Add spaces: Keepinmindthattheprisonerswerefacinga–forthem–totallyunknowngame.

Answer: Keep in mind that the prisoners were facing a – for them – totally unknown game.

Add spaces: Arcticseaice2013.

Answer: Arctic sea ice 2013.

Add spaces: Theoperator,whowasentrustedwithcodedmessages,wasisolatedinhisownlittleroom.Wecanseethesergeantbehindatelex-machine.

Answer:
The operator, who was entrusted with coded messages, was isolated in his own little room. We can see the sergeant behind a telex-machine.