So, I installed RC5 and then copied all the RC6 executables...
There was no advice whatsoever on where to get RC6 data.
Once i'm in-game (in the earth-view menu), i have no idea how to get back to the main menu (to save or exit the game): the blue top-right button named "Options" gives me hovering feedback, but when i click nothing happens.
In the end, i had to manually kill the program.
Another annoying bug: it happened twice in few minutes inside the Equip menu that the whole game hanged, mouse cursor and music included.
As soon as i switch to text mode (and then back again to X), everything restarts functioning like nothing happened.
This happened also with RC5.
I'm using a Debian Unstable (AMD32) with Fresh NVIDIA drivers.
One last thing, not really a bug.
I never played any XCOM, and i can't really understand why in the world shall i go to the "Aircraft" menu to equip my men.
Let's see if i can fight some aliens....