The latest updates (or some update within the last two weeks or so) to Microsoft Security Essentials and Windows Defender made them detect Drakefire Chasm as trojan. As far as I know, this is a false positive. The v1.3.2 zip has been sitting in dropbox unchanged for about 1.5 years and is quite unlikely it has suddenly become a trojan in there.
Interesting how Rogue Effect and Rings of Valor are clean according to Windows, even though they have been developed quite similarly (C++, libtcod, same compiler and machine), and shouldn't really have many differences with DfC. I guess there's just something with DfC Windows Defender doesn't like anymore.
VirusTotal result of DfC.exe: