Welcome to our forums Abened. I hope you'll find everything you'll need right here.

Sounds like an intereting project you got there. Do you already have something we can look at, or is it still in planning stage?

In any case, I don't think you will find free hosting services which allows you to install your game and use it the way you described.
I think your best option would be to get a fast internet connection to set up your own server.
However, before you even consider doing something like that, I 'd recommend building something first. By the time you have something playable, do some tests to see whether people want to play it or not. It would be a waste if you finally got your server up and running an nobody wants to play your game.