Gotten all warped from playing video games with 〜じゃう

Grammar Explanation: Doing completely or ending up doing with 〜てしまう and 〜ちゃう

Sacchan tries crawling on the ground to help find the cat that’s been stealing from the area lately. Kotoha takes this opportunity to step on Sacchan’s head.

さっちゃん:: 「歪(ゆが)みすぎだよ！」; “You're way too twisted!”; 「琴(こと)ちゃんゲームばっかりやってるからそんな風(ふう)に歪(ゆが)んじゃうんでしょ！」; “It's 'cause you only ever play video games, Koto-chan, that's why you've gotten all warped like that!”; Literal: “Because you do nothing but play games, Koto-chan, you end up getting warped like that, right!”

Key Points

1歪(ゆが)んじゃう = end up getting warped

歪(ゆが)んじゃう is casual speech for 歪(ゆが)んでしまう, from 歪(ゆが)む “to warp, twist, distort” plus 〜でしまう.

2Why じゃう follows ん

For verbs whose て-form ends in で, 〜でしまう contracts to 〜じゃう in casual speech.
歪(ゆが)む becomes 歪(ゆが)んで, then 歪(ゆが)んでしまう becomes 歪(ゆが)んじゃう.

3ゲームばっかりやってるから gives the blamed cause

ばっかり is a casual form of ばかり, meaning “nothing but” or “all the time”.
ゲームばっかりやってるから means “because you do nothing but play games”, setting up Sacchan’s explanation for why Kotoha acts the way she does.

4そんな風(ふう)に points to Kotoha’s attitude

そんな風(ふう)に means “like that” or “in that way”, referring back to Kotoha stepping on Sacchan’s head.
The phrase makes 歪(ゆが)んじゃう describe the way Kotoha has supposedly turned out, not a single action she just performed.

5んでしょ makes it an accusation

The ending んでしょ is casual のだろう, used here to press Sacchan’s conclusion onto Kotoha: “that’s why, right?”

ちゃん is an affectionate, informal suffix attached to names, used mainly for children, close friends, and family members.