Hi DEV!
A good start, I really hope you can include all the girls from the entire Dragon Ball franchise, whether it's the ones who appeared when Goku was little, or those from GT, Super, movies, filler and more... Since he has the time machine, that's possible. Also, I sincerely hope it doesn't turn into a sandbox game; there are already too many games of that type, and frankly, they're boring.
That's all for now, greetings and good luck with the game
P.S.: I hope there's no NTR, forced lesbianism, or femdom, and if you do include it, that it's avoidable, meaning the MC decides whether it happens or not.