So let's say I want to clone a game - that is, a clean-room reimplementation of the gameplay from an existing game. What that means is that I won't be using the intellectual property of the existing game - art, sound effects, code, music and all other assets will be original. What I will use are the gameplay concepts. I presume it would be fine to create a platformer game about collecting coins without getting sued by Nintendo. But what if one were to clone Tetris's gameplay exactly - down to the shape of the blocks, the gameplay modes, and the difficulty levels? What about creating a brand new RTS game, but having all the unit stats (damage, HP, etc.) identical to an existing RTS (say, Starcraft)? So to what extent is copying of gameplay legal? At what point does blatant copying of another game's gameplay slip into the territory of infringement of IP, if ever?

Quote: Original post by Sc4Freak
What that means is that I won't be using the intellectual property of the existing game - art, sound effects, code, music and all other assets will be original. What I will use are the gameplay concepts.

AFAIK, generally game-play idea by itself isn't really copyrightable. The design doc on paper, or a spreadsheet of game-play-related values would be though.

Quote: what if one were to clone Tetris's gameplay exactly - down to the shape of the blocks

I'd make sure no-one has patented those shapes for use in a falling blocks game ;) Otherwise it should be ok.

Quote: What about creating a brand new RTS game, but having all the unit stats (damage, HP, etc.) identical to an existing RTS (say, Starcraft)?

If you had all those stats in a big text file, and you just copied it verbatim into your own game (even if you change it 10% :P) then you've obviously just copied someone else's (copyrighted) work.
If you re-created the stats by tweaking it until you get the same game-play (e.g. "tanks kill men, men kill planes, planes kill tanks, etc...") then it's your own work.

Dude. Oh, wait. You're Australian. Mate.
This has been asked so many times. Read these:

http://www.gamedev.net/community/forums/showfaq.asp?forum_id=5#freegame
http://www.gamedev.net/community/forums/topic.asp?topic_id=547587
http://www.gamedev.net/community/forums/topic.asp?topic_id=546626
http://www.gamedev.net/community/forums/topic.asp?topic_id=546486
http://www.sloperama.com/advice/faq61.htm
http://www.underdevelopmentlaw.com/intellectual_property/

Quote: Original post by Tom Sloper

Quote: 5. What if the only thing I want to borrow is the gameplay - say, the idea of jumping on things and collecting coins?
Fine. Don't worry about it.

5½. So I can make a Mario game as long as it doesn't have Mario in it or have "Mario" in the title?
No. You also can't use the Mario music or sound effects, and you can't use any of the other Mario characters (you know, the ones who aren't Mario himself), and you shouldn't simply copy the Mario gameplay exactly.

^^Fixed ;P

Quote: Dude. Oh, wait. You're Australian. Mate.

What's that supposed to mean, buddy?

Quote: Original post by Hodgman

Quote: Dude. Oh, wait. You're Australian. Mate.

What's that supposed to mean, buddy?

Poor attempt at humor. Do Austalians say "dude" like we Californians do, pal?

Quote: Original post by Tom Sloper
Dude. Oh, wait. You're Australian. Mate.
This has been asked so many times. Read these:

http://www.gamedev.net/community/forums/showfaq.asp?forum_id=5#freegame
http://www.gamedev.net/community/forums/topic.asp?topic_id=547587
http://www.gamedev.net/community/forums/topic.asp?topic_id=546626
http://www.gamedev.net/community/forums/topic.asp?topic_id=546486
http://www.sloperama.com/advice/faq61.htm
http://www.underdevelopmentlaw.com/intellectual_property/

Thanks. Seems my google-fu is a bit weak today.

Anyway, the question is not really wether IP infringement is illegal; it's pretty well established that infringing on copyrights/IP of another party is a good way to get a cease and desist.

Rather, I'm wondering what exactly constitutes copyright infringement. As I understand it, the rules of gameplay cannot be copyrighted. But what exactly are the "rules of a game"? The specific values for damage, HP, and the like determine the way Starcraft is played, yet I'm pretty sure Blizzard wouldn't be too happy if I just copied these values down and used them in a different game to save myself the trouble of balancing the factions myself.

Perhaps I should provide something more concrete. I've been toying with the idea of cloning The Incredible Machine - a 1992 game published by Sierra. For those unfamiliar with the game, it involves building Rube Goldberg devices to solve tasks. The game gives you a number of parts, and a number of levels, and you need to use the parts to solve a task and complete each level.

A screenshot (of a newer version, but the same concept nonetheless).

My initial thought was to just outright copy the mechanics of the game - how the parts interact with each other and the like - and then build my own levels. Lasers can burn through ropes, candles can light explosives, torches can power solar panels, pinballs can roll down inclined planes, and so on. But are these specific gameplay rules copyrighted, or am I free to copy them?

Something more specific to your question about your current idea:
Take a look at Armadillo Run. That is, at its core, the same exact type of game as incredible machine. But it doesn't copy the game at all.

To quote Tom again. Think origional! Make up your own ideas, and your own game. The chances that you'd be able to copy all of game X in any reasonable time is fairly slim anyway. TheIncredibleMachine had hundreds of items and dozens of core interactions, and those all take time to implement and debug. So pick only one or two aspects of it, and start going. Add your own touches as you go and end up with something different, yet the same.

Just don't go copying the item set, the art set, the interface, the puzzles themselves, fonts, texts, title, menus, play field, etc. etc. etc.

Quote: Original post by Sc4Freak
Thanks. Seems my google-fu is a bit weak today.

Anyway, the question is not really wether IP infringement is illegal; it's pretty well established that infringing on copyrights/IP of another party is a good way to get a cease and desist.

Rather, I'm wondering what exactly constitutes copyright infringement.

Um. Yeah. Did you READ all those links in the 70 minutes between the time I posted them and you replied?

Quote: Original post by Tom Sloper

Quote: Original post by Sc4Freak
Thanks. Seems my google-fu is a bit weak today.

Anyway, the question is not really wether IP infringement is illegal; it's pretty well established that infringing on copyrights/IP of another party is a good way to get a cease and desist.

Rather, I'm wondering what exactly constitutes copyright infringement.

Um. Yeah. Did you READ all those links in the 70 minutes between the time I posted them and you replied?

Yes, although I couldn't find much relevant information in the underdevelopmentlaw link. Plus I'd already read through your FAQ beforehand. [grin]

Like I said, the issue is not whether or not copyright infringement is legal (it most certainly is not), and it's not about whether game ideas are copyrighted (because they aren't). Rather, what I'm asking is whether copying specific gameplay mechanics constitutes copyright infringement. The example I gave earlier (creating an RTS using unit stats from Starcraft) seems likely to be copyright infringement. But at the same time I've heard numerous times that gameplay mechanics can't be copyrighted. This post is interesting, but it doesn't quite answer my question (or I'm misunderstanding the post).

Quote: Original post by Sc4Freak
what I'm asking is whether copying specific gameplay mechanics constitutes copyright infringement.

And that has been answered (and in those references); there's no simple answer to this seemingly simple question. Your lawyer's advice should be sought before doing something that could get you sued.
And what can you get sued for? Pretty much anything, especially if you use ideas from an existing game.