RE: What is most important thing you want to achieve if you land in a different world?

The first thing should be to learn the rules of the world. In order to play, you must know the rules first!

After that, it's the pyramid of needs. It's the same in our world.
When basic needs are filled, you aim to fulfill higher needs.

At the lowest level you need food, shelter, water and air and to survive.
Then comes higher needs. Security, both physical and economical. Friends. Resources, like money.
After that even higher needs, like fullfillment and a reason to be.
After that you can aim to become a driving force in the new world. King, religious leader, maybe a god.