I'm enjoying this game. It's unusual to see an open-source game that someone could see you playing from over your shoulder, and think it was some big-budget commercial game. The art and music are very professional.
The program installed smoothly (from thr FreeBSD port), and it comes with an excellent HTML manual. I've played some roguelike games before, and given the limited amount of time I have for playing these days, it was frustrating that you had to memorize a lot of keystrokes and symbols that appear on the screen (or else spend a lot of time looking at a printout of the documentation). Falcon's Eye is cool because it lets you avoid all that. My three-year-old daughter was even able to move around the map!
I only have a few criticisms. (1) The isometric map is hard to read, and it's hard to tell whether you've gone everywhere it's possible to go on a level. (2) There doesn't seem to be any documentation for how you run the program, e.g., whether there are any command-line options. OK, you don't have to be a rocket scientist to type "falc" and hit the tab for tab-completion, but it would have been nice if "falconseye -h" had done the traditional Unix thing. (3) Some of the important commands are hard to find, e.g., you have to paw through the docs to find out that hitting S on the keyboard is the way to save your game and exit.
An open, cross-platform journaling program.
A scientific plotting package.