Sorry for this so long answer but here is what I have in my /usr/share/game/freera
.:
drwxr-xr-x 6 root root 0 Mar 30 20:35 data
-rwxrwxr-x 1 1000 1000 849871 Mar 21 23:45 freera
-rw-r--r-- 1 root root 0 Mar 30 20:37 toto

./data:
drwxr-xr-x 2 root root 0 Mar 30 20:34 gfx
drwxr-xr-x 2 root root 0 Mar 30 20:35 mix
drwxr-xr-x 2 root root 0 Mar 30 20:35 scripts
drwxr-xr-x 4 root root 0 Mar 30 20:35 settings

./data/gfx:
-rw-r--r-- 1 root root 1216 Mar 30 20:34 icon.bmp
-rw-r--r-- 1 root root 2238 Mar 30 20:34 icon.ico
-rw-r--r-- 1 root root 1705 Mar 30 20:34 icon.svg
-rw-r--r-- 1 root root 3049 Mar 30 20:34 icon.xpm
-rw-r--r-- 1 root root 617 Mar 30 20:34 map.shp
-rw-r--r-- 1 root root 867 Mar 30 20:34 repair.shp
-rw-r--r-- 1 root root 598 Mar 30 20:34 sell.shp

./data/mix:
-rw-r--r-- 1 root root 1456342 Mar 30 20:35 MAIN.MIX
-rw-r--r-- 1 root root 13764 Mar 30 20:34 MISSION.INI
-rw-r--r-- 1 root root 25046328 Mar 30 20:35 REDALERT.MIX
-rw-r--r-- 1 root root 35722 Mar 30 20:34 RULES.INI
-rw-r--r-- 1 root root 21632 Mar 30 20:34 SCG01EA.INI
-rw-r--r-- 1 root root 1895 Mar 30 20:34 TUTORIAL.INI

./data/scripts:
-rw-r--r-- 1 root root 77 Mar 30 20:35 hello.lua
-rw-r--r-- 1 root root 288 Mar 30 20:35 ui.lua

./data/settings:
-rw-r--r-- 1 root root 2118 Mar 30 20:35 files.ini
-rw-r--r-- 1 root root 922 Mar 30 20:35 freecnc.ini
-rw-r--r-- 1 root root 8154 Mar 30 20:35 freecnc.log
-rw-r--r-- 1 root root 517 Mar 30 20:35 internal-global.ini
drwxr-xr-x 2 root root 0 Mar 30 20:35 ra
-rw-r--r-- 1 root root 1137 Mar 30 20:35 songs.ini
drwxr-xr-x 2 root root 0 Mar 30 20:35 td

./data/settings/ra:
-rw-r--r-- 1 root root 3528 Mar 30 20:35 art.ini
-rw-r--r-- 1 root root 416 Mar 30 20:35 cursors.ini
-rw-r--r-- 1 root root 503 Mar 30 20:35 internal.ini
-rw-r--r-- 1 root root 845 Mar 30 20:35 protofiles.ini
-rw-r--r-- 1 root root 243 Mar 30 20:35 sidebar.ini
-rw-r--r-- 1 root root 11706 Mar 30 20:35 structure.ini
-rw-r--r-- 1 root root 3070 Mar 30 20:35 talkback.ini
-rw-r--r-- 1 root root 27985 Mar 30 20:35 templates.ini
-rw-r--r-- 1 root root 11508 Mar 30 20:35 unit.ini
-rw-r--r-- 1 root root 10155 Mar 30 20:35 weapons.ini

./data/settings/td:
-rw-r--r-- 1 root root 3496 Mar 30 20:35 art.ini
-rw-r--r-- 1 root root 262 Mar 30 20:35 cursors.ini
-rw-r--r-- 1 root root 693 Mar 30 20:35 internal.ini
-rw-r--r-- 1 root root 932 Mar 30 20:35 protofiles.ini
-rw-r--r-- 1 root root 486 Mar 30 20:35 sidebar.ini
-rw-r--r-- 1 root root 10480 Mar 30 20:35 structure.ini
-rw-r--r-- 1 root root 2257 Mar 30 20:35 talkback.ini
-rw-r--r-- 1 root root 19685 Mar 30 20:35 templates.ini
-rw-r--r-- 1 root root 7608 Mar 30 20:35 unit.ini
-rw-r--r-- 1 root root 4664 Mar 30 20:35 weapons.ini
-rw-r--r-- 1 root root 90 Mar 30 20:35 wsa.ini

Edit:
hum ok I now have a freera.log file:
Trying to load "TiberianDawnGold"...
WARNING: Missing required file "conquer.mix"
Trying to load "TiberianDawn"...
WARNING: Missing required file "conquer.mix"
Trying to load "TiberianDawnGold"...
WARNING: Missing required file "aud.mix"
Trying to load "RedAlert"...
WARNING: Missing required file "allies.mix"
ERROR: Unable to find mixes for any of the supported games!

new Edit :
Ok, so I put conqueer.mix nd allies.mix from my game and because I haven't aud.mix, I suppose it was sound.mix so I renamed it to aud.mix and put them in the mix folder.
But now, I have new errors, some others files are missing:
general.mix
demo.mix

But I have not demo.mix file in my game.

Too many problems :s