A problem of sorts usually sets in towards the end of the game in that the pace slows down considerably. Instead of feeling like there is more of a threat, is easy to achieve a sense of relaxation as you fall into completing your strategies and fewer gates open up. This seems to contradict the theme of the game, so today I decided to attempt a minor solution to the 'problem'.
http://www.sendspace.com/file/bcjiky
That link holds two new decks, as well as the rules for using them. These decks are the Rising Threat deck, which increases in activity the closer you are towards the end of the game, and the Final Hour deck, which comes into play only in the final moments. I'm not going to give a full rules explanation here, since the rules file should be adequate and it's not a large file.
I'm going to start testing this tomorrow, but it appears to be a final 'product' already. If you do try this out, let me know how it goes!