~WARNING: THIS INTEPRETATION SPOILS WHAT I ASSUME IS THE STORY.~

Well. The reason I'm writing this is actually to make sense of the ending, and why, in-universe, your character is even gathering the artifacts.
Let's begin!

You're a resident of Earth. Nothing too serious there, but there's... a strange machine on your planet that you have yet to understand. Why is it there? What does it do? You want to find out, so you look to the only possible option. Space.

Utilizing one of your planet's spare ships, you head for the skies. When you breach Earth's atmosphere, you decide to investigate the planet most resembling your own. Much to your misfortune, you discover that most of the local life is hostile, but one peaceful resident informs you of the "Universe Artifacts", four mysterious objects that were scattered across the planets long ago. Out of curiosity as to what exactly they are, you ask for their locations, and learn them. Venus, Neptune, Jupiter, and Mars.

It takes some struggles and nearly dying far too many times (Thanks, Mars Temple), to count, but you finally obtain all four, and bring them back to Earth.

Now, the strange machine. After dropping the artifacts a few times and having to stop some from rolling into the water, you locate each correct slot for each artifact and place them in, one-by-one. After they've all been placed... the ground begins to shake.

Panicked, you step back as a laser shoots itself out of the now-functioning CANNON, shooting up into space as rainbow-colored clouds form around the cannon. Once your initial shock wears off, you remember seeing another device similar to this one floating on a rock above Earth.

Hurrying to the ship, you board it and fly up, seeing the device now active. As you (somehow) manage to park it, you step towards the spiral, reaching out.

Making contact with it causes your entire body to jolt, and you're suddenly able to see both everything and nothing all at once, as your vision spins, and your balance fades, sending you toppling forwards as your sight goes dark.

...

When you awaken again, you're surrounded by darkness. You know you haven't gone blind, because you can see your body, but nothing else around you.

It's quiet. Too quiet.

As you get to your feet, you see something in front of you. Since there's nothing else visible, you hurry towards it. As you get closer, you see that it's an eye. A very ominous eyeball, but it's all that's left to see. Once you're in range, close enough to start to make out minute details, you find yourself almost flying towards it, being pulled by an unseen force.

The minute you hit the pupil, you're sprawled on the ground again, but there's something in front of you. Getting up to your knees, you notice that it's a sign. When you read it, you raise an eyebrow in confusion. "End of Universe," you read aloud.

...

The realization hits. This is the end of the universe. You were catapulted so far forward in time, that there's nowhere else to go.

Yet... a door opens. A door into pure white. Not wanting to stay here, you travel forward through it.

When you can see again, you're back at the device. Your ship is there.

You look back at the portal one final time, and step towards your ship, leaving the end behind.
______________

...Oops, this was longer than I thought it'd be.