You will get all kind of replies because everybody likes different things.
And then you would realize that you should decide to add ryona, guro, ponies, sci-fi, mechas, sluts, eroge, pure maidens, shrine maidens, danmaku, fps, 3D, 2D, dragon dildos and alchemist ninjas.
Making a game isn't so simple, for example you know right now what you want in your game (the time travel stuff), but you have no idea what it will be like. People traveling to the past? The future? Why they should make such a trip/what lead them to said time travel? If you don't have these things clear, you will start working in your project but as time passes you will feel it leads nowhere, because there was never something to work on. Asking others what you could do can give you ideas, true, but if you already don't know what exactly your game is about, then asking others to tell you thousand of ideas isn't a good way. You will feel that they sound good, but then you have to implement those things in your game, and things aren't that easy.
I'd suggest to first try thinking what you want to make, make some basic scripting, write about the character, design them, write the story (be it a scratch or whatever), etc. etc.
(btw you replied again while I was writing this)
>I think I want to be able to make 4 characters who attend the same school but accidentally stumble upon a time rift which leads them to another dimension.>In that same dimension their thoughts and pasts are slowly revealed and their friendship is in jeopardy.
Well, you have something now, start working on that, and first and foremost, include what YOU want to see in your game. Once you have some basic stuff release a demo, then people will tell you what you did wrong, what they liked, and what they would like to see.