Is it ok to say “Your barracks is finished”?

In the online game Travian, the following sentence is used:

Your barracks is finished. A good step towards world domination.

Shouldn’t it instead be:

• Your barracks are finished.

or

• Your barrack is finished.

"Barracks" can be either singular or plural.

Plural in the context of "one barrack, two barracks," etc.

But "barracks" could also refer to a COMPLEX of military installations. In that case, "your barracks is finished," means "your military complex is finished," singular.

Yes, it's "computergamese."

No, oddly enough, barracks is a singular as well as a plural. Barrack exists, but only in barrack block, one constituent of a barracks, or metaphorical contexts such as 'a gloomy barrack of a place'. And many computer games allow you to put a Barracks (and, e.g. a Temple) in each of your cities: I would think "Your Barracks are finished" would mean you have one in each city, similar to "Your Temples are finished".