If the ENG variable is set correctly (see answer by csgillis), try to narrow down the problem. Next make sure your Cygwin environment works correctly. Try compiling your code outside of Eclipse. To do this, open up a Cygwin terminal, change to the correct directory and type "make". If it builds game.exe and you can run it there, then there is an Eclipse setup problem. if it doesn't build game.exe, there is a problem with the Makefile or Cygwin installation.