Risk of Rain 2 is porting many things over from the first game, including the mechanic of artifacts. Artifacts are gameplay modifiers, like skulls in the Halo series.
The artifacts made interesting changes to gameplay like making it so the player only has 10% health but deals 500% damage or an artifact where you could pick your items instead of them being a random drop.
In Risk of Rain 1, there were several artifacts and some are making a comeback in the second game plus some new ones. But unlocking the artifacts could not be more different. There are a few intermediate steps involved now.
The Codes
To start off with, the only place you can begin to unlock an artifact is the Sky Meadow map, a map that’s making a reappearance from the first game. This is the fifth map in a cycle. You need to find a hole near the corner of the map and drop down it. Follow the path to a giant machine. Unless you get the alternate variant of the map, in which case you should drop off the side of the map onto the artifact machine.
In order to unlock an artifact, you need to have a code that you punch into the machine. Codes are scattered around the game and some definitely require some out of the box thinking. Conveniently, Hopoo Games has put a code right next to the machine.

There are four symbols in general: Cubes, circles, triangles, and diamonds. The code diagram will always be a top-down view. You punch those in the slots on the right and activate the machine using the computer just behind the camera in the screenshot. In this case, the code is squares surrounding a triangle. It’s worth noting that there are no penalties for getting a code wrong.
The Arena
Once you punch in the code, take the portal to a mysterious platform with an orb in the middle. In this arena, the effects of the artifact you are unlocking will apply but only in this location. In this case with the Honor artifact, all enemies in the arena are now elite enemies and will apply status effects.
Enemies will periodically drop yellow keys on death. Only the keys can damage the boss in the middle. Pick up a key and go run it to the boss in the center. Repeat until the boss is dead. Be sure to run over to where the boss was and pick up your artifact before you leave. The artifact will now be unlocked and ready to use on your next playthrough.