Open up a terminal and then type the following command to see the contents of the game's log
gedit ~/.ufoai/*/base/ufoconsole.log
If you want to, you can paste the last 60 or so lines of that file up here and that should provide enough information to figure things out.
Without having seen the log, it sounds as though your nvidia drivers may not actually be functional. Can you play any other 3d games? Try `sudo apt-get install extremetuxracer` (in a terminal, without the quotes) and then see what happens when you run that game.
Also, be prepared for a few of these minor hiccups as you dig deeper into linux. Consider them to be learning experiences and don't get discouraged. It is well worth the effort to learn linux. I have been running a linux desktop since 1996 and along the way I have converted a significant portion ofmy friends & family to it for day to day use. There is a definite learning curve and there are still a few unsmoothed edges but it can be done.