SDL 2.x support for Unvanquished now allows for better handling of window manager hot keys, multiple monitors, mouse motion, etc. It will also make it easier in porting to Wayland and other platforms with SDL2.
On the low-level side of the g ame that interests us the most, the Daemon engine also has many other improvements. Added this month was FXAA anti-aliasing support for its OpenGL 3.x renderer as previously covered on Phoronix. There's also improved multi-threading so the renderer can run in a seperate thread, improved IPv4 and IPv6 network support, and there's also now GeoIP support.
Some of the in-game changes for Unvanquished Alpha 20 includes new indicators, humans now have firebombs that can be thrown at aliens, and there's now bots in the release build that can be easily added to local games.
Unvanquished Alpha 20 also has various other minor features and fixes as this month's development release. More details can be found at Unvanquished.net. If you missed it, they are in the process of rewriting and modernizing their open-source game engine. The developers don't plan for this Tremulous successor to be in beta until 2014.