How to get better return of investment

I have a mobile game, in which i have user engagement of 10 minutes and user retention day 1 of 27%, I'm doing app promotion on Google Ads, so in USA and United Kingdom my CPI in Google Ads is 0,15$, But i still have ROI = 0,4, is that not too small?

Can anyone help me on some suggestions on what makes that so small? Thanks in advance.