After several crashes and having not a fucking clue what was going on; I decided to …
1) in terminal, create a Steam-logs dir in ~ (or $HOME)
2) right click on game
3) select Properties
4) under the General tab; click on SET LAUNCH OPTIONS…
5) enter the following: >> /home/YOURUSERID/Steam-logs/PROGRAMNAME-steam.log 2>&1
now; whenever the game crashes; I can easily (or rather more easily) try to find out what the hell went wrong.