Now I only have experience with one of the following engines (Torque) so correct me if I am wrong but it seems like most game engines from the demo and my uses with them are programmed specific around FPS including Irrlicht, Torque, C4, Cipher, Unreal, Source, etc... What I mean by that is that if you want to make a FPS game, you don't need to mess with the core engine code that much but if you want to make a RTS, RPG, Platform, or any other kind of game, you are going to have to moderately to heavily modify the core engine. What is FPS the standard for all game engines?

Because FPS games are the best selling genre for hard core gamers AND they're good for showing off cool tech because FPS games place the user into the world as the character.

I always thought it had more to do with how much it took to configure camera controls for something other than a "First Person" view. I remember when a number of classmates were all in a graphics class and had to do a simple game, the groups that just went with a straight up first person shooter all had it up and running in half the time compared to the groups that were working with a different style camera.

I'd say a few reasons:

1) There isn't a whole lot of room for new gameplay concepts in the FPS genre, so most of the differentiation from game-to-game is through the technology, so that becomes a much higher priority.
2) Unlike, say, RPGs, RTSs, or racing games, there aren't that many assumptions you can make about things on the rendering side like temporally-coherent views, or that you're going down a specific track (and hence the game can make a really good assumption on where you're going to be in 5 seconds or so).
3) Being FPSes and being right up in the action demands a high level of detail in a lot of areas: Geometric and texture quality, physics, animation, and so forth. Something like a racing game or RTS doesn't need that level of quality, typically (unless you're Relic :-P)

It's not necessarily universal that big engines have FPS's as their flagship title, though. I mean, Unreal 3's flagship was Gears of War; it's still a shooter, but it is a 3rd person one :-)

There is also a lot more information on how to write a FPS thanks to id's releasing the source to older games as well as public documentation on file formats, algorithms and the like.

i bet they are probably easier to test and get a feel for.

cause FPSs give you the largest space to swing your dick.
Talroth is correct though camera is easy in FPS'ers, camera is a big issue as someone mentioned gears of war (shooting actually is done in first person not 3rd person) cause its so much easier.
usually the players on the ground, restricting the FOV/objects seen.
why did most of the early FPSs take place inside rooms/dungeons? for this very reason.

though I think dick mana is the chief reason, I watched some video of killzone2 a couple of days ago, ATM its a >i>toss</> ;) up whos got the largest, them or crysis

I figure a fps is one of the the easiest games to make as long as you don't try to write your own model loaders or physics engine.

I blame id

I think a large reason for doing FPSs is that it gives a really nice way to showcase a lot of special effects (which makes for an easier sale). You are always up close to something, so showing fine details is easier. With something like an RTS, it could be more difficult to show the fine grained details that the engine is capable of displaying. A lot of FPS games have been technical showcases, so it only makes sense to compare yourself to your direct competitors.