[catapart]

Since you broached the topic, I've got an open curiosity about projects like that: if I manufactured entirely new assets, completely independently from the source game (possibly not even matching the source; like a different "skin" or "theme"), and then used those assets in a "clone" (in all but assets) of the source game, would that run afoul of IP law? I'm aware that anything can be litigated, but is there some quirk of IP protection for that kind of thing, or would I be able to use the cloned source with completely new assets without really infringing on anything? Does the cloned (re-coded? recomposed? clean-roomed?) source cause issues or create some kind of legal link from the original assets to the unrelated ones?

Again, just idle curiosity. No actual intentions here, so just wondering if anyone has some deeper knowledge on the subject.

[coldpie]

Game mechanics are not considered copyrightable[1]. If you had a clean room implementation with your own significantly different assets, it would be allowed.

However, the exact definitions of "significantly different" and "assets" is where things start to get fuzzy. While you could definitely make a very similar RTS game, exactly how similar can you get? EA doesn't own "military-themed RTS", but they probably do own "Soviets vs Allies with about 5 different unit types, air transports, and tesla coils." Getting even more fuzzy, are unit abilities considered assets, or game mechanics? It'd have to be worked out in court.

My gut feeling is these clone engines would probably lose in court. I think the specific expression of the general game mechanics being cloned here probably would constitute infringement. But there isn't much upside to the IP owners to pursue enthusiastic hobbyists cloning a 20+ year old game in a non-commercial way, so they let it slide.

[1] "Although Amusement World admitted that they appropriated Atari's idea, the court determined that this was not prohibited, because copyright only protects the specific expression of an idea, not the idea itself." https://en.wikipedia.org/wiki/Atari,_Inc._v._Amusement_World...

[philistine]

I'm sure if EA could undo their release of Red Alert and C&C as open-source, they would.

OpenRA simply downloads a copy that it loads for the purpose of assets, but the engine is completely new, and it is very different from the orignal Red Alert. At this point, I don't think a single unit acts exactly the way it did in the original game. It's endlessly being rebalanced.

[afavour]

IIRC if you make entirely new assets you're good to go. OpenTTD (Open source version of Transport Tycoon Deluxe) has its own custom made assets, but can also be used with the original if you own them.

https://www.openttd.org

Not sure it's ever been proven definitively in court, though. And if you "made" custom assets that were exactly like the original ones only with a 1px color difference or something I'm sure you'd fall foul of it. What counts as different "enough" is always debatable.

[mikepurvis]

It would probably be the usual clean room reverse engineering rules: one guy describes the assets to be cloned, and then another guy who has never seen the originals uses that documentation to create the replacements.

Once you've seen the originals, you're contaminated and no longer suitable for the role of doing the replacement work.

[catapart]

Oh, awesome! Yeah, this is a great example of something that I would have guessed would kind of be "over the line" being that it looks similar enough to be an issue. I'm glad it's not, though! But, either way, it's a perfect practical example of what I was wondering about, so thanks!

[afavour]

Unfortunately I think definitive answers are difficult to come by. No one cares that much about Transport Tycoon so no one is motivated to enforce anything. But if you made a clone of Call of Duty that had models as similar as OpenTTDs are to the original you might find yourself in hot water.

[wwfn]

https://freedoom.github.io/ does that for the still proprietary DOOM assets. Though the DOOM engine itself is open source, so a slight different situation than Command and Conquer.

[klaussilveira]

C&C is open source: https://github.com/electronicarts/CnC_Red_Alert/blob/main/LI...