The final boss in Sonic Frontiers will play out completely differently depending on your difficulty setting. If you're playing on Hard mode at the time the fight starts, you'll be treated to an extra hard bullet hell boss battle, one that's exclusive to players who have opted for this difficulty setting.
Anyone playing on Normal or Easy will instead skip the fight entirely, and instead just complete a few quick time events. This skips the bullet hell completely, but this is not surprising when you see how much of a difficulty spike it would be.
As someone who recently blasted through the game on Easy (hey, I had to finish it for the review!), I can attest to the fact that there's nothing in the game that warns you that your difficulty choice will change the final boss fight. Instead, this has been discovered by those who picked up the game around launch, and have quickly blasted through the 20-hour campaign.
Fans quickly realized that they were describing different final boss experiences, indicating that they had fought entirely different battles from one another. Now with footage able to be shared on social media, us lot who played on Easy and Normal can see what those on Hard had in store for them - and it definitely looks challenging. (It should be obvious, but spoiler warning for the video below).
The true final boss is called The End, and takes a lot of firepower and quick thinking to take down. Throughout the boss, The End hits you with all it's got, making it much harder than the other bullet hell segments earlier on in the game.
If you're struggling to make it through the game on Hard, fret not, as all you only have to up the difficulty right before the second-to-last boss fight begins. As long as you've got it set to Hard by the time Super Sonic launches into space, you're fine. This also won't affect the final cutscene, as that will play out the same regardless of how you took down the big bad.