2020 Update: Originally this post pointed you to Eltechs' website to install Exagear but I've since replaced it with my own guide to install it. box86 is a great alternative but I don't think it is usable for things like this yet and Exagear is still perfect for this.
Before you get started, install Exagear using the instructions found here.
Preparing the environment
To get started, enter the 32-bit environment and install required packages:
exagear sudo apt-get update sudo apt-get install libgcc1 curl
Downloading and installing SteamCMD
Once you have all the packages needed, move to a new directory and install steamcmd:
mkdir steamcmd cd steamcmd curl -sqL "https://steamcdn-a.akamaihd.net/client/installer/steamcmd_linux.tar.gz" | tar zxvf -
Then create an update script for CS 1.6:
/home/pi/cs16to where you want to install the server.
echo "login anonymous force_install_dir /home/pi/cs16 app_set_config 90 mod cstrike app_update 90 validate app_update 70 validate app_update 10 validate app_update 90 validate quit" > update_cs16.txt
Now to update your server run:
./steamcmd.sh +runscript update_cs16.txt
Running the server
Move to the directory and create a new script:
Change the arguments as you wish.
cd /home/pi/cs16 echo "./hlds_run -game cstrike -autoupdate -pingboost 2 -port 27016 +maxplayers 24 +map de_dust2" > start.sh chmod +x start.sh
Then you can run your server like so: