I'm sorry but, my abilities are not quite there yet, so I'll have to turn down your invitation.
My current skills not being up to par, I'll have to turn down your invitation.
あ～、そうですね。オンラインゲームはプレッシャーのヤバいタイプですね
「I'm sorry but, 」すみませんが「my abilities are not quite there yet, 」俺の実力はまだまだです「so I'll have to turn down your invitation.」それで今回のお誘いをお断らなければなりません。
「My current skills not being up to par,」今の私のスキルが足りないため「 I'll have to turn down your invitation. 」断らなきゃいけません
Because I still lack the ability (to perform well), I will decline the invitation this time.
私 – I
まだ – still
実力不足 – lack the ability (to perform well)
為 - because
今回 – this time
お誘い – invitation
お断り – decline
とあるゲームでクラブに誘われてタイトル文の通りにお断りしたい
I was invited by a certain game club but refused the suggestion of the title sentence.
オーストラリア 
日本 
