Exporting with smartphones in mind

A) Is "Left click" the action to use? Or something else?

C) How will resolutions be handled? If my game backdrops use a 1920 x 1080 resolution, what will happen to the exported game when you play it on, for example, an iPhone?

A. I believe multiple command interface types are valid for phones & tablets, but sure the single command interface is probably the easiest one to setup for compatibility on everything, though the coin/ring interface or even a retro button command interface might also be valid, though screenspace may be an issue with the latter.

B. I don't actually have a clue about this one as I don't own a phone or tablet & have never tried playing a game on one.

C. VS automatically scales games up/down to fit the available screen/resolution when in fullscreen mode, however a full HD game on a phone might not run very well. You have to plan your projects around your intended export platforms & be willing to compromise, or create multiple variation builds, or just hope for the best that your game will run smoothly on all devices you decide to export for.

There is, it's called compromise & optimization with specific targets in mind.

For example, you could use a default game resolution of 1280x720 (720p) & convert all of your images/animations to webp image format lossy 100% quality or less. Crop all backgrounds of images/animations. Create images/animations at 100% scale based on default game resolution - means don't create characters bigger than you intend them to be at 100% scale value. etc. etc.

There's lots of ways you can optimize your game projects, but I'm not going to list all the different methods that you can use or go in-depth about them as there's too many.

There's even an option when you export/build your game to convert to webp &/or scale the game up/down to a different resolution, but I highly recommend not using either of those options as they don't always work as intended, especially the option for scaling the default game resolution up or down.

here's an old guide I typed up ages ago with some tips on game optimization. It only covers some of the basics.

  - Left Click

  - Long Click (Click & Hold)

  - Double Click

No, the cursor will always be visible, clicking/tapping onscreen will show the cursor at that point until you tap again. So you must Remove Cursor images before export.