I would like to play Endless Space in French. Is there any way to do it? I use Steam in French already.
As you can see in the red marked box endless space is supporting french but text only (i used french steam store because you asked for french)
If you're still not able to start your game in french, try the following
Changing the language of individual games
The language of many games can be changed independently from the Steam client language.
Source: Steam How-To's