Based on http://www.blog.radiator.debacle.us/2013/12/reading-public-google-drive.html with modifications to prevent unreachable code warning, and to allow selection of specific sheets within the spreadsheet. http://stackoverflow.com/questions/11290337/how-to-convert-google-spreadsheets-worksheet-string-id-to-integer-index-gid http://en.wikipedia…

GDocService.cs

// To prepare a Google Spreadsheet for this:
// make sure the spreadsheet has been published to web (FILE >> PUBLISH TO WEB), which is NOT the same as sharing to web

// To use in a different script:
// 1) include "using Google.GData.Client;"
// 2) include "using Google.GData.Spreadsheets;"
// 3) call "GDocService.GetSpreadsheet( string spreadsheetKey );", see DebugTest section for sample usage

// uncomment to enable debug output
// #define debugTest

using UnityEngine;
using System.Collections;
using Google.GData.Client;
using Google.GData.Spreadsheets;

// for "InsecureSecurityPolicy" class at the end
using System;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

public class GDocService {
	// grab your spreadsheet's ID / "key" from the URL to access your doc...
	// e.g. everything after "key=" in the URL: https://docs.google.com/spreadsheet/ccc?key=0Ak-N8rbAmu7WdGRFdllybTBIaU1Ic0FxYklIbk1vYlE
	// make sure stop as soon as you hit an ampersand, those are additional URL parameters we don't need
	public static ListFeed GetSpreadsheet (string spreadsheetID, int sheetID) {
		// We need this fake certificate to trick Mono's security to use HTTPS... doesn't work in webplayer's security sandbox
		InsecureSecurityCertificatePolicy.Instate();
		
		SpreadsheetsService service = new SpreadsheetsService( "UnityConnect" );
		
		ListQuery listQuery = new ListQuery("https://spreadsheets.google.com/feeds/list/" + spreadsheetID + "/" + GetGoogleID(sheetID) + "/public/values");
		
		#if ( debugTest )
		ListFeed listFeed = service.Query( listQuery );
		Debug.Log( "loaded Google Doc Spreadsheet: " + listFeed.Title.Text );
		// Iterate through each row, printing its cell values.
		foreach ( ListEntry row in listFeed.Entries ) {
			// Print the first column's cell value
			Debug.Log( row.Title.Text );
			// Iterate over the remaining columns, and print each cell value
			foreach ( ListEntry.Custom element in row.Elements ) {
				Debug.Log( element.Value );
			}
		}
		#endif
	
		return service.Query( listQuery );
	}

	private const string cList = "0123456789abcdefghijklmnopqrstuvwxyz";
	private static readonly char[] cListArr = cList.ToCharArray();
	
	private static string GetGoogleID (int gid) {
		gid ^= 31578;
		string encoded = "";
		do {
			encoded += cListArr[gid % cList.Length];
			gid /= cList.Length;
		}
		while ( gid != 0 );
		return Reverse( encoded );
	}
	
	private static string Reverse(string text) {		
		char[] array = text.ToCharArray();
		Array.Reverse( array );
		return new String( array );
	}
}

// from http://answers.unity3d.com/questions/249052/accessing-google-apis-in-unity.html
public class InsecureSecurityCertificatePolicy {
	public static bool Validator(
		object sender,
		X509Certificate certificate,
		X509Chain chain,
		SslPolicyErrors policyErrors ) {
		// Just accept and move on...
		return true;
	}
	
	public static void Instate() {
		ServicePointManager.ServerCertificateValidationCallback = Validator;
	}
}