。
They came out on the attack in the first half.
Literal
First-half they [topic-は] push-push-mood [as-と] became.
Sports-commentary phrasing. 押せ押せムード is sports-journalism shorthand: 押せ押せ is a reduplicated imperative ('push, push!') functioning as an attributive noun, and ムード is the loanword 'mood, atmosphere' — together 'attacking mood, all-out offensive momentum.' The formal ~となる instead of ~になる gives a journalistic, written register. 前半 is the standard term for 'first half' in sports.