Why? Because I wanted to make a game that is already out, so I wouldn't have to design the sounds, graphics, levels, gameplay mechanincs and so on. This way I could learn how games are made in greater detail without all the hassle of thinking brand new game idea. And I know this might be hard to comprehend, but game development is my hobby, and I find it very enjoyable. That probably would be the biggest reason I do game development.

That only explains why you cloned the game. It does not explain why you want to risk a lawsuit by launching your game to the public. Since you know that you shouldn't, why?

If you want to be legit, then you'll have to remake all the artwork yourself from scratch.

Thanks Hodgman, but would it be sufficient enough to just remake all the artwork? What if did new artwork and I kept the exact same level design?

level design is also covered by copyright, all creative works are.

If you're just doing it to learn you could just keep the game to yourself (Even if that still might violate nintendos copyright in some jurisdictions the risk of anyonefinding out without you telling them is pretty close to 0)

This all begs the question of why you (or anyone) would want to do this. The world already has Super Mario Bros. You should make something new that the world hasn't seen yet and add something positive to the sum of human culture, instead of pouring in another "me too, me too" copy of something else.

Why? Because I wanted to make a game that is already out, so I wouldn't have to design the sounds, graphics, levels, gameplay mechanincs and so on. This way I could learn how games are made in greater detail without all the hassle of thinking brand new game idea. And I know this might be hard to comprehend, but game development is my hobby, and I find it very enjoyable. That probably would be the biggest reason I do game development.

So, now that you've done all that, why don't you keep the basic gameplay mechanics, but create your own levels, graphics, and sounds? Maybe even come up with one ability that wasn't in the original -- even something as simple as adding a double-jump has massive implications for level design. In fact, with a running engine today, you can almost certainly find volunteers to produce the new graphics and sounds, leaving you with level design and possibly implementing that extra ability.

I mean its up to you, obviously, but with just a little more work you can guarantee yourself to be in the clear, even to the point that you could charge money for it (to be clear, publishing your Mario clone as-is isn't any less illegal just because you do so freely, but Nintendo is more likely to come after you and less likely to treat you with kid gloves if you did).

Well, then I guess I won't be publishing this game after all. This will be my private little project.

Even if you do a mario clone, since you're doing this largely to learn, please consider doing some of your own art.. .I.e. maybe make your own version of the Mario character.. do a few custom SFX, etc.

You can learn a ton about game programming (and game development in general) by having a bit of knowledge of what the other disciplines have to do to get their job done ;)..

Even outside of the legality of the act, consider it from the point of view of a player. Say Joe likes Super Mario Bros. He's played it before, he's got the original NES version plus everything that Nintendo has done in the way of remakes and re-releases. He can beat it on a speedrun in 5 minutes flat. Now he wants to play something else, something similar but new. So he goes to Google Play (or any other service) and searches for Super Mario clone, because that's the nearest search term he can think of. Now he has to wade through entry after entry of literal clones, trying to find what he is actually looking for: a spiritual clone, rather than a literal clone. Granted, Google Play isn't so big yet that there are entries upon entries, but take it through its eventual progression and you can see that as more and more games are added, it becomes more difficult to find one among the crowd.

One of the largest problems facing indie and small developers on distribution platforms like Google Play, and pretty much in general, has been obtaining visibility in such a noisy and crowded market. The signal-to-noise ratio on some of those platforms is very low, at least partially because of so many direct clones being pushed. Releasing yet another literal clone, regardless of if you do so for free or not, just adds one more bit of clutter making the problem worse for everyone else, without any of the redeeming benefits of it being an original game that brings something new to the table. You're just adding noise, with no signal.

Now, you're proud of what you have accomplished, and you should be. Making even a literal clone of something is an accomplishment. But it's the kind of accomplishment that you share with your friends and family, and maybe on a personal blog or facebook or twitter; it is not the kind of thing that you share on a distribution service such as Google Play or Steam or anything else where you provide no benefit to the community at large in doing so, and in fact make the service just that much worse for the people that are trying to release original and new works.

Though releasing it to friends is still copyright infringement. And from the point of view of the problem you describe, a website is still something that gets found in Google results, so "competes" from that point of view. (And I'm not sure we can draw a hard line between websites and Google Play, they can both be mechanisms of distributing software - e.g., many sites like download.com are both.)

And I'm not sure I really agree - yes it's a problem of so much competition, but I don't think it works to say that the solution is that he shouldn't release his game, you could easily spin it the other way round and say his visibility would be higher if you didn't release your games. Some people might want to search for a similar-but-different clone, but some people might want to find the exact same game (to avoid hassle and difficulties of trying to run an emulator). And anyone advertising their game as "Super Mario clone", even if the game itself doesn't infringe copyright, could risk trademark infringement. I can perhaps understand why you might do that, due to the difficulties of gaining visibility, but it seems harder to get on a high horse - another game developer might complain that he can't get visibility for his game, because of all these non-directly clones that are crowding the market, getting higher up the search results, and creating too much noise...

From my own point of view as a user, I dislike how Google Play is so crowded out with adware - I'd certainly welcome more Open Source free and ad-free games, clones or not (not that I recommend it from the legal point of view - just that I don't see an ethical problem that it's creating noise).