Something like this?

Random fly-movement

It's just these events:

If you want it less drastic, you could always just set an instance variable instead of changing the angle directly and rotate 1 degrees towards it if the current angle is not between -1 and +1 of the new angle..

I mean stretch the layer in one direction.

Although stretching layouts/layers is not supported (I wouldn't recommend it for it changes the look and the feel of your game entirely), Most objects support it (tiled-background and tilemaps excluded) and as such creating a function to do it should be entirely possible..

As explained in this tutorial:

how to use the localstorage plugin:

In your on start of layout add an actiont to check if local storage item exists

add a new event to your event sheet:

local storage on item exist:

array load : localstorage.itemvalue

As far as I know you don't need a step inbetween..

When clicking/touching collision is detected for all objects under your touch/mouse..

If you want only the top instance to react:

on lightbulb touched/clicked

lightbulb pick top (instance)

add your actions

Why would you have to resize everything?

Construct2 does a great job at scaling..

Targetting different screensizes will always be some (and usually a lot of) work, especially with mobile screens switching from portrait to landscape so easily..

It might be my limited imagination, but what is the benefit of using the physics behaviour on a top-down game?

As a tank can only move forward in the direction it is facing, you could probably incorporate that in your events..

Could you explain in what way this would be useful?

I know the canvas plugin by rojohound has the functionality to get rgbaAt any x,y

From the manual:

"If a layer's Global property is set to Yes, then every layer in the project with the same name is overridden by that layer. The initial objects, as well as its properties, are used instead of the other layer's own content and properties."

to have objects on the layer keep their values etcetera, you have many choices..

Global variables, Global objects and saving to local storage, are the most used..

Supporting multiple screen sizes

Choose one of the fullscreen in browser modes

Remember the dotted area in the editor is your original view, which will be the reference for the scaling..

For elements on a layer with parallax 0,0 use the anchor behaviour if you want them to stay relative to corners..

If you want your game to be 16:9 choose one of the resolutions in the page I linked..

https://pacoup.com/2011/06/12/list-of-t ... solutions/

Art is made by artists..

If you are not yet a good artist, practice, practice, practice

You can find tutorials on designing sprites/game-art on the interwebs..

If you are not really good at drawing using vector-programs (like Inkscape or illustrator) might be better suited..