That's right, for there's no single place to put an app in Linux. There's no monolithic One Way To Do Things in Linux, no mandate from above, and the well-written guidelines (e.g., http://www.tldp.org/HOWTO/HighQuality-Apps-HOWTO/fhs.html which explain why take some time to find and read.
/usr/games all can contain executables, and
echo $PATH shows you the directories which are automatically searched on your system when an app is entered in CLI mode. Instead, Synaptic package manager is the way to go to find app executables; search on the app you want, and Synaptic will show you where the app's executable is.
If you do not have Synaptic, open a terminal window and do
sudo apt-get -y install synaptic to add it.