Leave the room where you spawned. Grab all the coffee and use the coffee machine to get another cup. You'll need it later.
The first bundle of money is "hidden" in the side corridor to the right.


Go back to the main room, but don't follow the arrows. Instead, rocket jump through the portrait of the bell pepper into the first hidden area.

You'll find yourself in the first hidden section. Once you get close to the corner, a section in the wall will open, revealing two enemies:

Defeat those and jump into the newly revealed alcove. You'll find a bundle of money and some coffee.

Continue following the path. As soon as you round this corner

an enemy will spawn. Defeat it and continue following the path. You will drop into the floor into a small room. Open the door and defeat the enemy in front of it.
Afterwards, go right and around the yellow pillar.

You will come to face another enemy. After defeating it, collect the money and coffee ahead.

Turn around, but be mindful of the two enemies appearing from the right. Defeat them, enter the door opposite to the previous stash. There you will face the Pink Helicopter, so be prepared for a tough fight.
After defeating the Pink Helicopter, go back to the previous room and follow the corridor opposite to the shaft you came from.

You will be teleported to another section filled with exploding bell peppers. Defeat them or run away prodding at the wall until you get back to the main area.

After leaving the first hidden section, rocket jump through this portrait:

You will enter another hidden section with a building in the center. Evade the cube's charge attack (or just blast it to bits) and enter the building. You will find several bundles of cash lying in the entrance.

Collect them, the coffee in front of the altar and the sausage inside the toilet in the right wing of the building before going back outside and leaving via the teleporter. You will come out of the same portrait you jumped into. Go towards the opposite wall. You'll find a spot that looks like this:

Rocket jump into the next hidden section.

Collect the bundle of money in front of you.

Turn left and follow the corridor. Mark will warn you to stop, don't. When you reach the end of the corridor, you will be teleported into a section that looks like this:

Make your way through it by rocket jumping. At the top of the staircase-like block, you will find a cow and a bundle of money.

Rocket jump onto the platform in the upper middle of the screenshot. You will find another bundle of money. Carefully make the next jump onto the small platform by edging towards the opposite end of the platform and then jumping. You might need some practice to make it. You'll find another bundle of money on there.

The next jump is comparatively easy. Simply rocket jump onto the platform with the treasure chest.

Once you "touch" the treasure chest, you will be teleported into a section resembling Minecraft. Get out of the house you spawn in while leaving at least one enemy alive, rocket jump onto one of the smaller trees.

(Not necessarily the one on the screenshot, but the first priority isn't the money, it's not getting killed by Minecraft Steve clones.)
From your tree, rocket jump onto the tall tree in the middle. You will find another bundle of money on the top.

Now, kill the remaining Minecraft Steve clones. You will be teleported back to the second part of the main area.

Make your way to the subway sign opposite to the area where the first trial is held. Rocket jump onto the small arc.

From there, rocket jump onto the diagonal bar.

Go upwards until the middle and rocket jump onto the small platform hanging from the ceiling.

Now that you have collected all the money, you should have about 60k. Confidently take the elevator next to the subway, bribe Jürgen with a sausage and collect the rest of the money needed to open the golden door by playing video poker. Start with small bets until you figure out how to win.