Maybe this will help:
View attachment 4467463
You need money to level up and every monster drops money. It isn't called money, but the concept is the same. You can see how much money you have in your character menu (press X), it is the number at the bottom of the screen.
You can level up in any safe room where you can access the big glowing door.
Passive skills have a point value. You can increase the characters max point value in the Potential: Grant Menu. The very first option will allow you to purchase items that increase your max points.
You need to rescue 4 companions that are 'on the map somewhere'. The entire game is one giant maze that you need to navigate through, so explore, explore, explore.
The trigger to unblock an area or passage is usually marked with a pulsing green square. If you can't access it from the map you are on, there is a route from another map that you have to find.
Some areas are blocked off until you rescue certain companions. Any icon that that show a character's head, requires that companion to be rescued before you can unlock that particular gate.
When you get sick of fighting everything on the map, there is a 1 point passive skill in the Explore tree that will let you auto win any battle where you are 10 levels higher than the enemy. It still opens the battle screen, but it is an auto win, so just hold the CTRL key down and fast forward through the text.
Pressing D on the keyboard will bring up a menu with a quick teleport option as the first menu choice, it can teleport you to any safe zone you have unlocked,