How do I create little minigames?

I want to make an arcade where the player walks around with UI that tells the player how much money they have.

I already have the UI and stuff down but what I need help with is this.

I want the player to walk up to an arcade machine and it pops up with a Do you want to play this game? message.

If the player answers yes I want the player to teleport to another layout but with different UI like a timer at the top. It hides their money and the other UI from the lobby.

When the time runs out I want another message to pop up with how much the player won and if he/she wants to play again or go back to the arcade.

I feel like this is very simple but yet it seems hard.

Also if you can tell how to change perspectives like Top-down to Sidescrolling that would be great.

Thanks in advance.

Use Demonorie's store system. Use another layout for the minigame.

Give me a Pixel

Which specific part are you having difficulty with? Is it the whole game concept or a certain aspect of it?

Money:

You'll need to store the amount of money in a LocalStorage so that you can add to it and retrieve it later on. Everytime you retrieve it (or set it), you can put it in your global variable and then set the text to the global variable. Check out the LocalStorage documentation, which is really helpful if this is your first time dealing with LocalStorage.

Changing layout:

When changing layout, if you don't want to display the money UI, then don't include it, destroy it, or hide it.

Platform/Top down

There is no switching of perspective really. You just define it by what behaviors you use and how you construct your levels. For example, if you have a player and put a Platform behavior, then you have a side scrolling game. Add solid objects for the player to jump on. If you want top-down, then give your player 8-directional movement and design the layout as such. You can disable or enable if you need to have both.

There are some basic fundamentals you are curious about so let us know if you have specific questions to the challenges you are facing. Good luck! :)