Learn Hardcore German: Im Projekt müssen wir eng zusammenarbeiten. - In the project we have to work closely together.

So im Projekt literally means in the project and is just the normal, more natural way to say it. Both in dem Projekt and im Projekt are grammatically correct, but im is what you actually say in everyday German.

Why is Projekt capitalized?

In German, all nouns are capitalized, regardless of where they appear in the sentence.

das Projekt (the project)
Im Projekt (In the project)

So Projekt is capitalized simply because it is a noun. This rule is much stricter than in English.

What case is Projekt in here, and why?

Projekt is in the dative case: dem Projekt → im Projekt.

The preposition in can take either dative or accusative:

Dative = location, no movement (Where? in the project)
Accusative = movement into something (Where to? into the project)

In this sentence, we are talking about the context or setting (within the project), not moving into the project. So in takes the dative here:

in dem Projekt → im Projekt

If there were movement (e.g. We are going into the project), you would use ins Projekt (in das Projekt, accusative).

Why does the sentence start with Im Projekt instead of Wir müssen …? Does that change the meaning?

Starting with Im Projekt is mainly a matter of emphasis and style, not meaning.

German is a verb-second (V2) language: the finite verb (here: müssen) must be in the second position in main clauses. The first position can be occupied by:

the subject (Wir müssen …)
or another element like a time phrase, place phrase, object, etc. (Im Projekt müssen wir …)

So both are correct:

Wir müssen im Projekt eng zusammenarbeiten.
Im Projekt müssen wir eng zusammenarbeiten.

The second version puts a bit more emphasis on the context im Projekt (in the project), but the basic meaning is the same.

Why is it müssen wir and not wir müssen after Im Projekt?

Because of the verb-second rule in German main clauses.

Position 1: Im Projekt (a prepositional phrase)
Position 2: the finite verb → müssen
Then comes the subject → wir

So the structure is:

Im Projekt (1) müssen (2) wir …

If you start with Wir, then wir takes position 1 and the verb still must be in position 2:

Wir (1) müssen (2) im Projekt …

In both cases, the finite verb stays in second position; only the element in first position changes.

Why is wir used and not uns?

Wir is the subject pronoun (we) in German.
Uns is the object form (us).

In this sentence, wir is the subject doing the action:

Wir (subject) müssen (verb) eng zusammenarbeiten (infinitive phrase).

You would only use uns if we were an object, e.g.:

Sie helfen uns. – They help us.

Here we are the ones who must cooperate, so wir is correct.

What is the role of müssen here? How strong is it?

Müssen is a modal verb expressing necessity/obligation. In this sentence, it means something like:

We *have to work closely together.*
We *must work closely together.*

The obligation can be:

objective (because of project requirements, deadlines, etc.)
or subjective (speaker’s opinion: this is necessary).

Compared to other modals:

sollen – should / supposed to (often weaker, more about expectation or recommendation)
dürfen – may / be allowed to
können – can / be able to

Here müssen is quite strong: cooperation is necessary for the project.

Why is zusammenarbeiten at the end of the sentence?

In German, when you use a modal verb like müssen, the main verb goes to the end of the clause in its infinitive form.

Structure here:

müssen = finite modal verb (in second position)
zusammenarbeiten = infinitive main verb at the end

So:

Im Projekt müssen wir eng zusammenarbeiten.

Compare:

Without modal: Im Projekt arbeiten wir eng zusammen.
With modal: Im Projekt müssen wir eng zusammenarbeiten.

The modal verb (müssen) takes over the conjugation; the other verb stays as an infinitive at the end.

Is zusammenarbeiten one word or two? And is it a separable verb?

Zusammenarbeiten is a separable verb and is written as one word in its basic dictionary form:

infinitive: zusammenarbeiten
base verb: arbeiten (to work)
separable prefix: zusammen- (together)

In simple present without a modal, the prefix separates and goes to the end:

Wir arbeiten eng zusammen. – We work closely together.

With a modal verb, the verb appears as an infinitive at the end, and the prefix is not separated:

Wir müssen eng zusammenarbeiten.

So:

arbeiten … zusammen (finite verb)
but zusammenarbeiten (infinitive form at the end)

What does eng mean here? Is it “narrow”?

Literally, eng can mean narrow/tight, but in this context it is used figuratively to mean closely / in close cooperation.

So eng zusammenarbeiten means:

to cooperate closely
to work in very close coordination
to collaborate intensely / tightly

It does not mean physically close in space; it’s about the quality and intensity of the cooperation.

Why is there no article before eng or zusammenarbeiten?

Because eng and zusammenarbeiten are not nouns here:

eng = adverb/adjective (how we work: closely)
zusammenarbeiten = verb (to work together)

Articles in German are used with nouns (das Projekt, ein Auto, die Person), not with verbs or adverbs.

So the structure is:

Im Projekt (prepositional phrase)
müssen (modal verb)
wir (subject)
eng (adverb)
zusammenarbeiten (infinitive verb)

No place for an article in that part of the sentence.

Could you also say Im Projekt arbeiten wir eng zusammen? What’s the difference?

Yes, you can say:

Im Projekt arbeiten wir eng zusammen.

Difference in meaning:

Im Projekt arbeiten wir eng zusammen. – In the project, we work closely together.
- A neutral statement of fact or description.
Im Projekt müssen wir eng zusammenarbeiten. – In the project, we have to work closely together.
- Adds necessity/obligation (we must do it; it’s required/important).

So the original sentence is not just describing how you work, but emphasizing that close cooperation is required.

Could you say an dem Projekt or bei dem Projekt instead of im Projekt?

You can, but the meaning shifts slightly:

im Projekt – in the project (within the project setting / as part of it)
an dem Projekt (often am Projekt) – on the project (focusing more on the task or work on a project)
bei dem Projekt (often beim Projekt) – with/at the project (more like in the context of that project, often used for participation or involvement)

All three are possible in some contexts, but:

Im Projekt müssen wir eng zusammenarbeiten. emphasizes within this project as the environment where close cooperation is necessary.

Using am Projekt or beim Projekt would be understood, but may sound less standard/natural in this exact sentence and could subtly shift the focus.