Learn English – Hard to watch or difficult to watch

As a native speaker, I would understand I am seeing a film to mean the speaker intends to go to a theater to watch a film in the future.

I'm going into the city tomorrow.
--What are you doing there?
I'm seeing a documentary about global warming.

"I am watching a film" would mean that the speaker is currently engaged in the act.

Phone rings.
Hello?
--Hi, it's me, Tom. Do you want to shoot some hoops?
No, I'm watching a film at the moment. How about tomorrow?

P.S. Seeing a movie refers to the occasion of going to a theater (or some other venue) in order to watch a film:

We're seeing a movie at the new Ritz theater on Friday night.

or to the attendant physical circumstances or mode of the screening/viewing:

Seeing a movie in IMAX is a very different experience from seeing it on an iPad.

Watching a movie refers to what the audience is doing as they become immersed in the film and the story it tells.

You can be interrupted while watching a movie. You cannot be interrupted while seeing a movie.

"More difficult" does not necessarily mean "hard".

I will explain using a parallel, around the words "heavy" and "heavier".

1. A piece of paper is light (i.e. not heavy).
2. A banana is heavier than a piece of paper.
3. A helicopter is really heavy.

Now, lets analyze the "banana": is it heavy? Actually, no; nobody would really call a banana "heavy". Because "heavy" is reserved for other objects, like "cement brick" or "helicopter".

It is the same in the original example. "More difficult" does not (necessarily) mean "hard". Maybe it is still easy to learn, but not as easy as other games.

"How hard" vs. "How easy"

Actually, in this context, they are both OK and they mean the same thing. Since hard and easy are not measurable, the answer cannot be really short, like: "42". Ok... 42 what? The answer to these questions is usually an explanation, where the listener can make his own mind.

A very good example from @JasonBassford, posted in a comment (thank you):

Airplanes are very complex pieces of machinery—yet it's very simple for passengers to sit in seats while traveling in them.