The Yolk-Star™'s design is heavily based on the Death Star from the Star Wars franchise. It's a huge egg with a metal ridge below the center, dividing the spherical part from the more oblong one. On the oblong part rests a window which is surrounded by five laser cannons. The Yolk resides inside of the giant structure. It appears to be its power source, and it can use the machine however it wants.
The Easter edition makes its shell rainbow colored, while the Christmas edition does not change it at all.
The Yolk-Star™ is encountered once at the end of the last chapter.
In the first phase, the Yolk-Star™ is inside of the protective shell. It will constantly use the Lasers attack. It has 80000 health. Once its health is depleted, it will crack, regain 80000 health, and use Chicken Call once. It will also spawn two Gifts and two Atomic Powerups every crack. Cracking it once more will result in it using Chicken Call twice. The third crack results in it using Chicken Call three times in a row, and the fourth one results in it using that attack four times in a row. Once it's cracked for the fifth time, the protective shell explodes, giving you one million points, and it spawns five Atomic Powerups, which moves you right to phase two. The Yolk-Star™ has in total 400000 health in this phase.
In phase 2, the Yolk reveals from the recently destroyed shell. Its only attack is Yolk Wobble, where it wobbles around, trying to hit you. It gets more aggressive the closer it is to exploding. It also becomes redder, and the egg white surrounding it gets smaller with more damage. Once its health is depleted, the Yolk explodes and splats as a fried egg on the screen. The Yolk has in total 200000 health in this phase. Once the fight is over, you will receive the following points: 400000 for defeating the Yolk, 100000 for every remaining life, and 10000 for every remaining Missile.
The laser cannons are valid targets, but attacking them won't damage the Yolk-Star™. Auto-lock weapons aren't very recommended for this reason. Don't get too greedy once it drops Powerups, as they will be surrounded by Terminator Chickens and lasers. When Terminator Chickens appear, simply use a Missile to dispose them. In the second phase, simply move out of its way once it goes to the bottom of the screen, and get as many hits in as possible when it's high up.
- The Yolk-Star™ is one of the only bosses from Revenge of the Yolk and its sequels to not have any strengths and weaknesses.
- The Yolk-Star™ can drop the Utensil Poker even if you haven't unlocked it yet, which isn't a bug.
- It parodies the Death Star from the Star Wars franchise.
- By extrapolating its size and comparing it to other bosses, we can find out that the Yolk-Star™ is roughly as big as Earth, and the same size as the eggs shot by The Egg Cannon, its successor.