envvariable="value" %COMMAND%
Closing as the question has been answered.
If somebody want to know result. I modified /home/zenitur/.local/share/Steam/SteamApps/common/Awesomenauts/run_game.sh
#!/bin/sh
LANG=ru_RU.CP1251 ./Awesomenauts.bin.x86
It doesn't solve problem.
Nothing extracted yet.
I live in Russia and I often play Awesomenauts game. I didn't see correct messages from russian gamers. But if I start this game in Wine emulator, I see correct messages. I want try to add LANG=ru_RU.CP1251 parameter, but it needs to be add before "./Awesomenauts.x86" string. Is it possible to do with "Set launch options"?