Here is what I interpreted from the remarkably abrupt ending of Limbo (with some background first):

Our unnamed traveler of this volatile world has been searching for his sister.  Throughout his journey through Limbo, his encounters have all put him in immediate danger if not resulting in multiple gruesome deaths.  From chapter to chapter, the difficulty or survival is quickly growing.  In the early stages, there are bear traps, and other children who are most likely the inhabitants of Limbo.  These inhabitants were just like our Boy at one point:  Lost.  These hostiles gave in to their environment and absorbed it, while our Boy it fighting it.  

Once chapter 24 is reached, the Boy is faced with one final puzzle.  When it is completed, one of the most breathtaking scenes I've ever witnessed occurs:  The Boy, mid-air (apart of a puzzle), breaks through what appears to be a glass wall (while in slow-motion, nonetheless) and soars though a familiar forest until finally landing on the ground some time later.  Now, for me, this scene rewarded me with the biggest feeling of relief ever.  All tension has died at this point, and the player feels at rest, if you will.  

So now comes some crazy Deja Vu.  Once the Boy has been laying on the ground for a few moments, the player realizes that this is the same situation that the game kicked off with.  So the same thing happens here, the Boy opens his eyes, blinks, and slowly stands up.  Control is given back to the player and they will continue on at their own pace for about thirty steps...

There she is. Your long lost (maybe?) sister, kneeling below a tree house, looking down at the ground.  The player loses control of the Boy at this point and he begins slowly walking towards his sister.  He stops, leaving some distance between them and waits for her to react.  She halts, lifts her head, turns, and theirs eyes meet. Suddenly, the screen goes black and the credits appear.  

After the credits are finished, it goes back to a screen of the tree house, with nothing but flies occupying it.  I personally think that this means that both the Boy and his sister are already dead.  Flies had appeared hovering over dead bodies during the early to middle sections of the game.


So the flies to me represent that Boy and his sister have died in the real world.  These deaths occured in the same location, but in much, much different ways. 

In the real world, the Boy and his sister were playing together in their newly built tree house in their back yard.  This is a normal situation. The Boy looks up to his idols such as superheroes, and professional athletes, while his younger sister likes dolls and watching Nick Jr. This girl trusts her brother and loves him very much, but the brother is reluctant to show his appreciation for her.  So in the tree house, the Boy decides to play a game, whatever game it is a favorite of his and his sister breaks a rule.  Boy gets out of hand with his imagination, or possibly gets angered by his sister not knowing the rules.  One way or the other, out of his spur-of-the-moment furiousness for her, he shoves her, intending to knock her down.  The sister stays a-foot trying not to fall and reaches the edge of the tree house.  The Boy realises what is happening and jumps out to help her avoid the fall.  He grabs her by the hand as she slips over the edge of the tree.  Now he is holding her, keeping her from her death as she hangs on to his hand.  The Boy, as young as he is, cannot hold her.  The Boy never gave up though.  Instead of releasing his sister from his grasp, he gets pulled with her, falling to his death alongside his sister.  

When the Boy wakes in Limbo, he knows he could never forgive himself, but perhaps he could earn forgiveness from his sister; if only he could find her in this world.  The enemies of this World are compiled from Boy's imagination, which he has turned on himself.  As his search for his sister comes closer to an end, his resistance also builds.  Shattering through the broken glass at the conclusion represents forgiveness from himself, and he is given a direct path to his sister.  His sister was not placed in the "other world" of Limbo for good reason.  She was without sin, just an innocent child.  The world where she is is closer to a purgatory scene, because of her being right where she was left in the real world.  So Boy shattering through the glass is him being forgiven, by himself or by his sister (or both).  From there the rest is given, their eyes meet and the credits roll.  

Ok, done.

Sorry for the bulls**t background story but I feel it set the mood in the right place.  

By the way, I did not find all the eggs.  Braid had 8 stars and when those were found, the ending was the "real" ending.  So tonight I am going to start searching for the remaining eggs and I will post

Tell me your interpretation or add on to mine, I would love to hear other ideas!  This whole story is up for interpretation so I am not saying I am right, leave the negative comments aside please.