How fix "Failed to initalize authentication interface"?

"No Russian" (Íè ñëîâà ïî-ðóññêè)

Old engine doesn't support any symbols besides english, so...
Check your directory so that there are no unsupported characters ("space" supporting)

Ñòàðûé äâèæîê íå ïîääåðæèâàåò äðóãèå ñèìâîëû, êðîìå àíãëèéñêèõ, òàê ÷òî...
Ïðîâåðü ðàñïîëîæåíèå èãðû, ÷òîáû â àäðåñå èãðû íå áûëî íåïîääåðæèâàåìûõ ñèìâîëîâ ("ïðîáåë" ïîääåðæèâàåòñÿ)

HACKERMAN

1. Press Win+R and input "regedit"
2. Íàæìè Win+R è ââåäè "regedit"

1. Find folder "ComputerHKEY_CURRENT_USERSoftwareValve"
2. Íàéäè ïàïêó "ComputerHKEY_CURRENT_USERSoftwareValve"

1. Delete folder "Half-Life" and "Steam"
2. Óäàëè ïàïêó "Half-Life" è "Steam"
3. ReRun Steam (RMB on icon Steam in tray -> Exit)
4. Ïåðåçàïóñòè Steam (ÏÊÌ ïî èêîíêå Steam â òðåå -> Âûõîä)

Profit