All people talking about Unreal, great points. I never heard of it but I will look into it and make a decision. Unity really seemed easy to learn and develop with but what you are saying makes a lot of sense.

To Unity fanboys, is it really that sloppy/inefficient you think?

PS: I was thinking making the game a browser game like deadfrontier, Unity seems to make it easy, i don't know about Unreal.

While I agree with the advice that was given about Unreal Engine, I don't think they knew you were developing a browser game. Most people saying they want to make an MMO mean they want to make an MMO that will finally dethrone World of Warcraft. Had you posted screenshots of Dead Frontier instead of Diablo, people probably would have reacted very differently and had far more advice and far less ridicule.

Dead Frontier uses Unity, so obviously Unity will work if that is your goal. You can look up a game's Wikipedia entry, and you'll often see what engine they use.

Please don't try to start a flame war by telling Unity fanboys that anyone said it is very sloppy and inefficient. Unity is just fine for most uses, and I think even fanboys will admit you're unlikely to see the next Call of Duty release being powered by Unity.

Personally I am not a fan of UnrealScript. I have done some work in UDK and even written an article (http://www.gamedev.net/page/resources/_/technical/game-programming/using-c-managed-dlls-in-udk-r3203) or two about using it, however for the game project I am currently working on we abandoned UDK in favor of Unity.

When using UDK (without source code access of course) it seems that you are very tied into the Unreal way of doing things. The editor and graphics capabilities of UDK are top notch, however I think Unity provides more flexibility when it comes to programming possibilities.

I think others might be neglecting the fact that unless you have some serious cash and connections or are an established studio (in which case you might not be asking this question) you will NOT have C++ source code access to the Unreal engine in the current version. That is just not going to happen period. According to http://devmaster.net/devdb/engines/unreal-engine-3 :

Cost is estimated to be more than $700,000

In that case then UDK is not a C++ engine but an UnrealScript one for development (with the possibility to use DLLs, but that will not work on mobile).

Also keep in mind that for UDK 4 UnrealScript is being dropped in favor of C++. http://forums.beyondunreal.com/showthread.php?t=198378 . I do not know if it is a good idea to invest in a proprietary scripting language that is being replaced in the future. At least coding in C# or a standardized language provides potential that some of the source code base could be moved over to other technologies. UDK 4 might be a good option for a C++ engine (assuming there is a version for indie developers that has C++ available...) but that is going to be some unknown amount of time in the future.

I am assuming the people who developed the games on this list: http://unity3d.com/gallery/made-with-unity/game-list found that Unity performed reasonably for them as they were able to create games in it.

I wonder for instance if the developers of the game https://www.mwtactics.com/landing/ from the above list realize that they really need the power of C++ to save them from having to completely start over? How embarrassing for them indeed.

I am not a Unity "fan boy", but I do think it is a decent tool. I am not a fan of the fact that the pro version costs $1500 or that other licenses for other platforms cost even more for instance... however it seems to be a fair price if you are an indie studio serious about creating a game.

Realistically unless you are a major AAA game studio I think Unity is a reasonable choice. It may be true that no AAA games have been created in it and it may be true that it is not the ideal choice if you are after extreme performance, but that does not mean that it is not an acceptable choice for an indie game or for a beginner.

Anyway the true answer is pick the right tool for the job period. Perform a technology evaluation and consider your specific needs when picking technologies. Do not just blindly jump on ANY bandwagon no matter how much it is recommended. Pick technology based on REQUIREMENTS.

I've always loved this kind of post when I see them, completely vague on details that only come out when the OP starts getting frustrated when people are being honest with them. I have to say that this is part of the fun of being a developer, doing the research yourself. The fact that you can post pictures of what you want it to be like means you can research what engine and tools were used to make them and then, if the engine isn't one available to hobbyist and indies, you search for a engine that can do similar things as the one used. Also, as pointed out, when you say you will "hire" or "hiring" programmers/artists/etc. it implies that you will pay them for their services. Target platform also changes your research as some engines don't offer web game abilities. Lastly, it doesn't matter how vague or specific you had made the first post as people can find room for speculation in every absence of detail in a post, action, comment...it is just how humans are.

Though, you should always try to be specific on everything, for example, you didn't mention it was a web game during your first post which was an important piece of information as it narrows down engines that can be used.

As for your questions:

What I need to know is, what technology should I use? What software does one use to achieve what I want to achieve? Should I go Unity? Should I build it from scratch using some engine? Which one and why? What should I use to do the art part? What's the general process of developing a game such as mine?

Those are too vague to answer specifically and will require you, as I said, to research games like what you are wanting to do and that will answer all those questions for you.

Consider looking into Hero Engine or another engine primarily designed with server scalability in mind. I can't help you on design. Plenty of good books on it to be read for the cheap with a safari online subscription. I know Earnest Adams has a couple new ones out on strategy and world creation genres, that might help some.

For art, it really depends on what the artist you hire prefers. There are also plenty of stocks art packages out there for sale, if you don't need an entirely original art set. The asset stores of the various engines targeted at Indies are a good place to start.

My personal favorite 3d package is Modo. That said, it's more a matter of workflow than any real sense of capability. Blender3d is an amazingly powerful app, if you want to look into making some of your own models. Making good 3d models is a lifelong discipline in and of itself though, as is rigging/animation and texturing, so unless you enjoy making it, there are usually better ways of getting it.

Good luck.