Topic: Developing simple Ruby game. Some beginner questions.

I would like to write simple on-line game in Ruby.
For start only with single player mode.
I did some research about writing games in ruby and i found this two links:

> - - simple game with server based on sinatra

> - - ruby game library

But im thinking this maybe is an overkill.

Assumptions of game:

    Turn-based game
    Two players
    Each player have 10 pawns
    Each pawns have diferent ability(speed, armor)
    Pawns moves like in Chess
    Pawns can throw a ball
    Board with 64 fields

Another questions:
0. How to setup game board for Ruby game?
1. Should I write this only in RoR and Jquery??
2. Which gems should I use to add multiplayer to this game in future?
3. Maybe the easiest way is write this with rubygame?
4. But how to develop this game online?