Learn German: Zwecks unseres Überlebens errichten wir sofort einen Unterschlupf. - For the purpose of our survival, we build a shelter immediately.

The preposition zwecks (for the purpose of) requires the genitive case. Since das Überleben (survival) is a neuter noun, the possessive pronoun unser gets the -es ending, and we add an -s to the end of the noun.

Why does the verb errichten come before the subject wir?

This is due to the standard V2 (verb-second) rule. The entire prepositional phrase Zwecks unseres Überlebens takes up the first position in the sentence. Therefore, the verb must take the second position, pushing the subject wir to the third position.

Is zwecks used a lot in everyday spoken German?

Not really. Zwecks is quite formal and usually found in written, bureaucratic, or technical contexts. In normal conversation, a German speaker would be much more likely to use an um ... zu clause here, such as: Um zu überleben, errichten wir sofort einen Unterschlupf (In order to survive, we build...).

What is the difference between errichten and bauen?