Logging

[RandumKiwi]

...
#AssaultCube
*.*;auth,authpriv.none;local6.none; -var/log/syslog
...

If you have AC running on local6 (the default facility), specifying local6.none to syslog is simply going to cause AC not to be logged by the system at all. You need to then point local6.* to a file, eg.

[SELECT ALL] Code:

# Save AC messages to AC log
local6.*                          -/usr/games/ac/logs/callisto.txt

Incorrect, as he's attempted to make AC direct somewhere later (see "if $syslogtag"... rsyslog's different to normal syslogd).

Stab in the dark, from my own testing. I think that it's your AC config... one small whitespace makes a tonne of difference:
-N MCastle = local#28763
-NMCastle = NCastle

Of course, this all depends on how you're issuing these command line options... so, please, run the server, and give me the output of your log that goes like this (or similar):
logging started: console(INFO), file(DISABLED), syslog(INFO, "AssaultCube[MCastle]", local6), timestamp(DISABLED)