This is exactly the same problem I am having.

Can someone who has actually published a web app with C2 give us some insight on this?

A Google search reveals that virtually no one else has this problem, so I wonder if it's C2-related.

Nevermind, I guess there is a way to detect platform...

https://www.scirra.com/manual/110/browser

This is what it looks like without full-screen:

<img src="http://i.imgur.com/qlpcshP.jpg" border="0" />

Anyone have any idea what's causing this?

Try downloading the latest release here and trying it again.

<img src="http://i.imgur.com/3HSc0uh.jpg" border="0" />

Firstly, before anyone points me to the tutorial on supporting multiple screen resolutions, let me say that I have read it and that my game's resolution is 1136x640, or exactly the same as the iPhone 5's resolution.

This is what I see when a user fullscreens my game. Does anyone know what causes this?

I'm doing this already.

However, Android users may touch the screen and end up using touch controls when they have a keyboard. Considering Android screen sizes vary by phone model (they're not consistent like iPhones are), this means the actual gameplay area is smaller than if they used the keyboard.

But as I said, there are Javascript libraries that detect what kind of platform the app is running on. What we're doing right now is a hack to accommodate different types of input. Why can't C2 integrate one of these libraries or otherwise detect the phone platform?

I am definitely interested. Can you share?

You can use this: "On any touch" and enable an entirely event sheet after this, and doing your sprites to appear on this code (setting them invisible doesn't mean they will be untouchable, so, only create then when any touch is detected is a better way to go..)

There is somewhere an option called "touch screen is detected", or "on touch enable", I remember this option but was unable to find it.

Good tutorial:

https://www.scirra.com/tutorials/202/touch-controls-and-a-trick-to-detect-input-method

JavaScript plugins exist for detecting platform. I would love to see one integrated into Construct 2.

What you described works, but it's a hack. Suppose the user is on Android, which is on phones with a keyboard, but that user touches the screen. Given that Android devices vary in screen size, I would prefer the user play with the keyboard instead of using touchscreen controls, which would take up 1/4 of that player's screen at the least.

When checking for touch on a specific object, is that object's collision polygon used, or the entire sprite box?

Bump. An answer to this would be really nice. Do I need to use a plugin?

My game has on-screen touch sprites that will appear if they are on a iOS device, but these shouldn't appear on a desktop or any other platform that has a keyboard of some kind.

How do I determine whether the player is on iOS or on a desktop?

That's probably better off being posted in the Your Creations subforum.