We need to complete the idiomatic expression pick up the pieces, which means to try to return to a normal situation after a shock, disaster, or tragedy.

We need to complete the idiom throw in the towel, a metaphor originating from boxing that means to admit defeat or give up.

A relative pronoun is needed to a defining relative clause that describes the game. Both that and which are grammatically correct here.

We need to complete the inversion structure Not only… but also….

We need to complete the phrasal verb set out, which means to begin a course of action with a specific aim or intention.

The sentence uses the inversion structure Such + be + noun + that… for emphasis. Such modifies the singular noun demand to emphasize its massive scale.

The sentence uses the emphatic inversion structure So + adjective + auxiliary + subject + that…. Unlike such, So must be used here because it directly modifies the adjective popular.

We need conditional linker meaning on the condition that.

The sentence uses the conditional expression If you happen to…, which emphasizes a chance or accidental occurrence. It fits before the infinitive verb to come across (similar to If you should chance to meet).

The adjective astonished is commonly followed by at or by, meaning very surprised.