IS A MAIN PROTAGONIST ESSENTIAL?

I don't think it's essential to have one particular protagonist who outshines the rest; there have been plenty of works that didn't have one.

Just as the first example off the top of my head, A Song of Ice and Fire has a multitude of characters but no "main" one. FF1 just had four warriors of light. You could actually argue that having a main protagonist in your cast is somewhat disingenuous since in real life nobody is any more special than anyone else, and if all your characters have an engaging storyline there's no need for any one of them to completely take centre stage.

Absolutely not!
My game doesn't have a main protagonist and I think it turned out well. It's nice to have a balance between a lot of characters instead of focusing on one. The game also avoids the player from getting bored of the same person over and over again. Having a game with no main character in my opinion adds so much more variety.

Well, kinda does depend. If the story is all about growth and one's journey, then yeah, it would probably suffer if there was no central character.

I think SaGa Frontier has something like that, in a "everyone is doing their own thing, with a few connections".

author=kory_toombs
A protagonist is not necassary, what if your
game is not about the good guy, what if it is about
the bad guy? Then your main character could be
the antagonist.

The definition of both protagonist and antagonist have nothing to do with good or bad. A protagonist is a character that your story revolves around, and has a goal they desire to achieve. The antagonist is a character or element that's designed to prevent the protagonist from achieving that goal. While "good guy vs. bad guy" is a common archetype for this, the protagonist and the antagonist have nothing to do with morality, so much as how they operate in your plot. This is why we have "anti-heroes" in some stories.

On the topic at hand, I kind of agree that you don't need a single protagonist, but be careful about it. The reason a lot of stories revolve around a single character is because it's much easier to handle, and with multiples, you can risk creating a plot-line that feels unfocused and confusing, as too often the case with DBZ-like anime. Besides, I feel like there is always going to be one character the audience will root for more than others, so I wouldn't say a single protagonist is easy to avoid.

It's not entirely necessary but you're really making it harder for yourself if you go the other route. The main character is there so that we have someone to identify with and care about. If you don't have a main protagonist you better have a damn good story.
At least, that is how it is in my experience, if we are talking ordinary story-driven games.
Obviously, if you're making something like Pong, a main character is of little importance.

What if you had a game like Breath of Fire 4,
but focusing more on the good guy and bad guy equally.
And then at the end of the game choosing which side to take.

I think it's obvious by now that you don't need one, though I feel that if you're not careful, you may accidentally end up with a main protagonist. You'd probably have to be diligent if you wanted to make your game devoid of one.

A "main" character simply means that the attention is being focussed on one character instead of many. By not using a main character, FFVI style, you're using a "main group" instead.
The only way to not have any main characters at all is to make a game like Tetris.

The question then becomes less about whether you want one or many main characters, but about whether or not you want to develop the character/background/story of one or many characters.

If you only have one character who you want to develop and build and follow around, he'll inevitably become the "main", even if that character isn't the most important for a story. For example, FFX's "main character" was completely and utterly irrelavnt to the central story and could probably be removed without changing the story at all until the end, but the game focusses infuriatingly on him and his ilfe and story and memories, so he became the "main" despite Yuna being the important one.
FFVI didn't have a main not for lack of importance, but because many of the characters had equal development and interest. Similar in a sense to the Big Bang Theory tv show: Leonard is clearly the "important" character with which the story revolves around, but there's no "main" character in the show; it's about everyone.

So...do you have one character you'd like to develop and reveal to the world with a cast of others less interesting, or who revolve around him...or do you have many to talk about?