S3TC is off by default. Maybe you'll have to rebuild Mesa with this option on.
By default MesaLib does not come with S3TC enabled by default, but you can use the txc_dxtn external extension library located here:
To add dynamically loaded S3TC support into Mesa for applications that may require it.
The Team Fortress 2 multiplayer game developed and published by Valve on Steam for Linux has been updated yet again and the devs have made numerous changes and improvements.
Team Fortress 2 has been in the top ten most played on Steam for years and nothing seems to slow it down.