Converting a string to coordinates
Well I don't now coffeescript, but guess I can read it anyway :D

I think both are good and readable.
I don't know if you can add empty lines to the code. If you can:

strToCoordinates = (input) -&gt;
    halves = input.split(',')
    if halves.length isnt 2
        console.log 'Please enter coordinates in format: x,y'; 
        return

    [x, y] = (parseFloat s for s in halves)
    unless isInteger(x) and isInteger(y)
        console.log 'The coordinates must be integers.'; 
        return

    if not inRange(x, y)
        console.log "Coordinates must be between 1 and #{GRID_SIZE}."; 
        return

    {x, y}


But this really is a minor arguable tweak (some will like it, some don't, I do).
Another point would be the "overuse" of returns. Functions are easier to read, if they do have lss return-statements. But Again, this usually applies to larger functions only.