I thought about considering "ideas" to be a separate category. But I decided against this notion, because we do not even credit humans for ideas most of the time. You usually cannot protect an idea. The implementation of an idea is covered by copyright. But not the idea itself. Some big companies try to invoke patents there. And if your "idea" involves certain implementations you might touch on trademark laws. But anyone can implement a block pushing game and how levels look will overlap.
To elaborate, yes, ideas, story, game rules and other things would be a separate category that is currently not asked in the ai disclosure. But the dislosure question is quite specific about content. The idea of content is not the content itself. You cannot buy an idea asset in the store.
If you were to have an idea and implement it with ai tools, you would have to tag the appropriate implementation methods.
But if you were to ask for an idea and would implement it by hand, you would not have to tag this. You could ask an AI to create a reference image of how a pose looks, and then hand draw your original character in that pose.
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Why I would allocate a game level under code, is because a level is the variable states for the code. It is made to be interpreted by that code. In a computer science way interpreted. Where you read an X or a O, the code will read a wall or a hole. And it will treat those as a wall or hole, no matter if you hold it in memory as a character in ascii. It is not merely displayed, it is symbols that literally codify the level. There is a pun here somewhere about literal outsourcing ;-)
Even if you consider it to be of the idea category, the implementation of that level is still code.
I do expect them to say that they used AI assistance in general.
You cannot do that with the Itch's questionaire if used as the thing tells you to use it. And most importantly, players cannot filter for this with the filters provided.
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An interesting question. I shall counter with something similar I wrote a while ago.
There is a bucket full of machine made bricks. The kid toy kind. A kid builds a playhouse with those toy bricks. Is the house human made or machine made ;-)
To answer your question and solve the apparant paradox. It depends on the context and what you are asking specficially.
For one thing, AI have no agency. Your AI director does not exist. There needs to be a human operator telling the AI to do this and you can default to that operator as the director of the work.
For Itch specifically, the question is about content. It is literally about assets plus code. The meta content of how those assets are ordered or why you chose specific assets, is not asked. But if you fused them together with an ai (the cutting), that would be code.
If there were a thing like ai disclosure for movies, there would be all sorts of positions where ai could do things and thus be disclosed in credits. That would be director, editor, cinematography and such things in your example.
For the playhouse, the house would be human made. The assets that make up the house would be machine made. But no one credits the parents for encouraging the child to build a house and explaining how a house looks and that it will fall apart if you do not have walls to hold the roof.