Create a new user (https://www.cyberciti.biz/faq/howto-add-new-linux-user-account/ )
Switch to that user
Go to /home/username/ or ~
Upload cs2d files into a folder there
do "chmod +x cs2d_dedicated"
run cs2d using screen, tmux or similar
Don't use chmod 777 on more than one file ever. It completely disables all permission systems implemented in Linux. Only use root account when absolutely necessary, even then you should try to use sudo instead. Using root for anything allows for attackers to completely take over your system. CS2D definitely has some security issues that could be exploited to gain control over the user it's running on. In case of a new user just for cs2d, that's not too bad, in case of root it's bad.