Ni elektis novan tabulludon por la ludvespero.

In Esperanto, -is marks the past tense. So elekti is the basic verb to choose, and elektis means chose or did choose.

A quick comparison:

• elektas = chooses / is choosing
• elektis = chose
• elektos = will choose

So Ni elektis ... tells you the choosing happened in the past.

The ending -o marks a noun, and the extra -n marks the direct object.

So:

• tabulludo = board game
• tabulludon = board game, as the thing being chosen

In this sentence, we are the subject, and the new board game is what was chosen, so it gets the accusative -n.

Because adjectives in Esperanto agree with the nouns they describe in both number and case.

So:

• nova tabulludo = a new board game
• novan tabulludon = a new board game, as the direct object

Both words show the same grammar:

• nova → adjective
• novan → adjective + accusative
• tabulludo → noun
• tabulludon → noun + accusative

This agreement is very regular in Esperanto.

Esperanto has no indefinite article. There is no separate word for a or an.

So a bare noun often corresponds to English a/an:

• tabulludo = a board game / board game
• nova tabulludo = a new board game

Esperanto does have a definite article, la, which means the.

Por usually means for.

In this sentence, it shows purpose or intended use:

• por la ludvespero = for the game evening / for game night

So the idea is that the board game was chosen for that occasion.

Tabulludo is a compound word:

• tabulo = board
• ludo = game

When Esperanto makes compounds, the first part usually appears as a root, without its final -o:

• tabulo → tabul-
• ludo stays as the main noun

So:

• tabul- + ludo = tabulludo

The double l happens naturally because tabul- ends in l and ludo begins with l.

It is another compound word:

• ludo = game
• vespero = evening

So ludvespero literally means something like game evening, often understood as game night.

Again, the first word appears as a root:

• ludo → lud-
• vespero stays the main noun

So:

• lud- + vespero = ludvespero

La means the, and it is used when the speaker has a specific thing in mind.

So la ludvespero suggests a particular game evening that the speakers already know about, such as:

• the regular weekly game night
• the planned game evening this weekend
• a specific event already mentioned in conversation

If it were not specific, Esperanto might simply say por ludvespero in some contexts, but here la makes it sound like a known event.

Yes, Esperanto word order is fairly flexible, partly because the accusative -n helps show what is the object.

The normal order here is:

• Ni elektis novan tabulludon por la ludvespero.

But other orders are possible, for example:

• Novan tabulludon ni elektis por la ludvespero.
• Por la ludvespero ni elektis novan tabulludon.

These can change the emphasis, but the basic meaning stays the same.

In Esperanto, the subject usually does not get any special ending. The object is the one that often gets marked with -n.

So here:

• Ni = the subject, we
• novan tabulludon = the object, what was chosen

Because ni has no -n, and tabulludon does, their roles are clear. This is one reason Esperanto can allow flexible word order.