Zither Emperor - Volume 5 Chapter 35.1

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

Through an array of coincidences, Alex comes to learn that making pills is one of the best ways to earn money in the game, 'Eternal Cultivation.'

I returned after 10 years.

Wei Suo, a low level cultivator from the Spirit Peak City was scammed in a transaction. He ended up purchasing a damaged low level magical treasure. However, this worthless damaged magical treasure had an artifact spirit that already lived for several tens of thousands of years… On top of that, compared to several tens of thousands of years ago, many of the rare and sparse things were abundant now.