When you have small SSD disk, you can't be a gammer on linux :/
A simple way to solve that is to use this script to move you steam storage folter to an external HD, to install as many games as you want!
Just copy the mount-steam.sh
script and run it like:
sh mount-steam.sh <Your external HD name>
sh mount-steam.sh my_external_hd
WARNING: After that you will only be able to use steam with your external HD connected!