I posted this thread in the lounge because I think this is where it belongs, and I like the post quality when people are in the lounge...
So should I use Java that enables players to play from browser or can download game client, or use C# or C++ for better graphics, faster processing, and less system requirments, but will require me to build different build for Mac & Linux, which I will take care later on.
or use different methods do develop the game?

"fully motivated to make a video game since could not find right one"

"I have started in a small secret MMO RTS project that is unique last year"

if its truly the case that you've discovered a game type you want to play that isn't already out there, and you want to make it, then you are most fortunate. if this is indeed the case, then i'd recommend pursuing it, despite its complexity.

start with the simplest possible rapid prototype - no networking (if possible), no audio, and just enough graphics to tell whats going on. get that working, playable, and at least semi-balanced. then add the next step - networking, then graphics, then audio.

do you research first. determine the target user and the target platform. figure out the COMPLETE suite of tools to do it all: compiler, network lib, graphics lib, audio lib, low level stuff like timers and math, paint programs, 3d modelers, audio file editors, etc. make sure you can convert asset file formats between all the tools. select the tools that will get the job done fastest - including learning time.

much of your time will be spent in learning. by thinking first, and not rushing into things until you're sure what you're doing, and with a lot of patience, and a couple of years, you'll have your game.

a complex game as your first project simply means much more to learn and do before you get results. most folks don't have the stick-to-it-ivness to see such a project through to completion. that's why its not usually recommended. i'd only recommend it if you've found a game that meets the magic criteria of what to build: "what do you want to play, that's not already out there?". if you have found a game like that, then develop the concept incrementally in small baby steps and rapid prototypes, basic gameplay, networking, AI, graphics, audio, etc. and keep the design as simple as possible to start. you can get fancy in later versions, once its proven itself worthy of a new version. the real trick is to select and test your tools in advance so you know you'll be able to do the entire thing without having to change tools mid-stream. then you can proceed with relative confidence that you will reach the end of the tunnel if you keep on trudging. and avoid the temptation to switch to newer more advanced tools as time goes on. if you fall into this trap, you'll spend all your time learning the newest API's and porting the game to them, and never make any actual progress on completing the codebase, just updating portions thereof. continuous graphics improvements alone could probably be a full time job if take to the extreme.

Don't use the term MMO because I don't think it's what you mean. You're talking about people starting up their own servers which is more along the lines of just a multiplayer game. Plus if you say you're a new developer working on an MMO, you're likely to attract negative responses since one person simply can't do it. If you don't believe me, go find a "simple" mmo, and look at the credits screen for it. Count the number of people and assume they worked on the project for 1-2 years...

And if you've never completed a project, you may want to set your sites a little lower. Give this article a read:

http://www.gamedev.net/page/resources/_/technical/game-programming/your-first-step-to-game-development-starts-here-r2976

It walks you through the early projects you should complete and why you should.

- Eck

but I have difficulty choosing which one to use, I have started scratch projects in all of C, C++, Java, C# and PHP but never fully completed one, because I then switch to another language and recode the algorithm again, I am just not sure which one to use.

whatever will get the job done with the least development time. so the language has to be capable of doing what's required, and running fast enough on the target platform. all the tools and libraries required must be compatible with the compiler and language used. what language and library specifically is totally irrelevant. all that matter is that it works, and its the fastest way for YOU to complete the game, including learning time. tools should be selected based on productivity.

so make a list of all the tools that could do the job. for each tool, estimate how long it would take you to learn the tool and then use it to make the game.

whatever set of tools adds up to the l;east amount of total learning and development time is the correct choice for you.

note that this makes tool selection a very personal thing. its based on the dev's current knowledge level, and what tools they have access to. for a given game, the correct answer might be different for two different dev's based on previous knowledge, existiing in-house code, and budget constraints.

i personally have experience with c++ and the dx9 fixed function API, along with an in-house game development library of low level stuff. so unless i need graphics beyond the capabilities of dx9, the answer for me for just about any game is c++, dx9, and my Z game library. they can do anything that dx9 can do, and i already know them, so learning time is zero.

but the real message to take away here is that its how PRODUCTIVE a tool makes YOU that should drive tool selection. and that is measured in estimated learning time + estimated development time to complete the game. and obviously the tool must be capable of the job in the first place. other than having the basic needed capability, and how productive a tool makes you, no other factors should really be considered, except perhaps tool price vs budget constraints.