I'm saying yes too. While it's somewhat subjective whether Unity is the best, it's certainly one of the best. Its particular strengths in this area are:

• easy art import pipeline
• easy depolyment
• easy to use physics
• easy to set up advanced materials and shader effects

It's particularly well suited to individuals or small teams, and you can deploy commercial products with the free version (until your company passes a certain relatively high turnover threshold).

If you download the free version to test it out, here's a great way to try out just how fast you can get a prototype up and running. You can get a first person WSAD + mouse controlled view around a scene in minutes.

1) Create a new project, and be sure to include the "standard assets" package

2) Either:

• Make a small "placeholder" scene in Unity using a large plane for the ground, and place boxes around for buildings/walls.

  or

• Make a test scene in a 3d app, consisting of a floor plane and simple obstacles / buildings / walls. If you choose this option, you need to:

  • export your scene as an FBX into the "Assets" folder of your new project.
  • make sure "Generate Colliders" is ticked in the scene's import settings in Unity.
  • drag a copy of your scene from the project pane into the hierarchy pane.

3) You should now have your scene visible in the "Scene View". (If not, select your scene's root node in the hierarchy, then move the mouse over the scene view and hit "F").

4) We're going to add Unity's ready-made first-person controller, which has a built-in camera, so - Delete the current "Main Camera" object from your hierarchy pane.

5) In your "Project" pane, look in Standard Assets -> Prefabs. Drag the "First Person Controller" prefab from there into your scene.

6) Move the First Person Controller in your scene to the desired starting position.

7) Hit play, explore your new scene using mouse to look, use WSAD or Arrow keys to move and strafe, and hit space to jump!

8) when you're ready to add weapons, AI, multiplayer or other effects, just search this site!

Yes, for making FPS's, Unity is the unparalleled greatest tool of all time. Here is an incredible tutorial to get you started. Many of the fine users here are also at your service if you should need more help making the next Halo.

I think yes. And I have a shoot script for you to put here. Remember to name the javascript "Shoot" or something like that. here is the shoot code:

var speed = 3.0;
var speed1= 100.0;
var gunPrefab:Transform;
var hit:Transform;
private var shoot = false;
var gun;
var runing = false;
var dtime=0.0;
var muzzel:Transform;
muzzel.renderer.enabled=false;
var time1=0.0;
function Update () 
{
    if(Input.GetButtonDown("Run"))
    {
    hit.gameObject.animation.Play("run");
    FPSWalker.speed = 12.0;
    runing = true;
    }
    if(Input.GetButtonUp("Run"))
    {
    hit.gameObject.animation.Play("runc");
    FPSWalker.speed = 6.0;
    runing = false;
    }
    /*if(Input.GetButtonDown("Fire2"))
    {
    if(runing==false)
    {
        hit.gameObject.animation.Play("aimdown");
        shoot=true;
        FPSWalker.speed = 3.0;}
    }*/
    /*if(Input.GetButtonUp("Fire2"))
    {
    if(runing==false)
    {
        hit.gameObject.animation.Play("ashoot");
        shoot=false;
        FPSWalker.speed = 6.0;
    }
    }*/
    if(time1==0)
        {time1=Time.time;}
    if((time1+0.25)(smaller)=Time.time)
    {
        muzzel.renderer.enabled=false;time1=Time.time;
    }
    if(Input.GetButtonDown("Fire1"))
    {
        FPSWalker.speed = 6.0;
        if(colision.GUN_AMMO(bigger)0)
        {
            muzzel.renderer.enabled=true;
            audio.Play();
            gun = Instantiate(gunPrefab, transform.position, Quaternion.identity);
            gun.rigidbody.AddForce(transform.forward *speed1);
            colision.GUN_AMMO
            FPSWalker.speed = 3.0;
        }
    }
}

and note, remove all sorts of animations/sounds if you do not have them.

Yes, Unity is best, but is realy realy hard to make a game in it. :)

How i make a game in it? I have see 20 videos on YouTube but i cant still make a game. Please help

I have used Unity and I absolitely love it for its simplicity. BUT i will have to disagree with almost every answer here because the few multiplayer FPS's I have played that have been made with unity are so laggy that they are no fun to play.

Ofcourse you can argue that this can be fixed with decent planning and hard core programming skills, but I think you'd be better off just going with UDK that is more specifically tailored for your particular request (multiplayer fps).