Lawsuits.

I imagine the revenue distribution would follow a power law here. So it would only really make sense for Epic to go after non-compliant "whales", where the unpaid royalties exceed the legal costs.

Also, the more profitable the project, the lower the non-compliance rate, probably. It makes little sense to defy the royalty agreement if you have a successful project.

I would phrase it "contracts" - which has the implication that if you violate the contract, you may be sued. Contracts are how just about everything is "enforced". I think that programmers tend to think that if something is required, we must have programmatic protections in place that ensure it actually happens. Most of the world does not work like that; they rely on contracts.

To handle noncompliers, they can get off of the various App stores with a simple DMCA request, no complicated lawsuits required, unless the developers appeal the take down, which probably involves a lot of "under penalty of perjury" lying.

Why would breach-of-contract have anything to do with the DMCA?

I assume cma is suggesting that the contract would allow Epic to revoke the license of anyone that failed to pay their 5%.

Once Epic exercises that right, any further distribution of the product would be a violation of Epic's copyright and Epic could file a DCMA takedown.

Because the developer doesn't own the copyright to the engine?

It's unfortunate that this model really only works for large developers serving broad markets like gaming.

Whereas if you're an indie developer writing image processing code for example, it is going to be hard to find infringers and harder to strongarm them into coughing up licensing fees.

I expect this has the effect of keeping source code behind closed doors that would otherwise be public.

They don't necessarily need to do a lawsuit. They could just shut down your UE subscription until you file the relevant proof of earnings.

You don't need the subscription to work with the engine, its a GitHub repository you can just locally clone.

So a state-of-the-art graphics library, a critical component to your new, moderately successful video game, doesn't deserve 5% of the revenue?

Yeah, if you think you can write your own alternative to Unreal Engine for less than (revenue-$3000)*0.05 per quarter, then by all means, you should do that.

Competion is a wonderful thing.

I can't build a decent car for less than the cost of a low end BMW. But, there are plenty of other companies than can.

So, the real question is what are the other options out there and I suspect there are few engines that can come close.

iDTech is no longer licensed for third-party use; only Zenimax properties can use it. CryEngine is available -- they have a $10 a month subscription plan that is royaly-free, but you don't get source code access like you do with Unreal Engine here. (They offer seperate terms for source access.[1]) Unity exists, but I don't think it's in quite the same tier as Unreal (although for some projects that may not matter).

[1] http://cryengine.com/get-cryengine

Perhaps not, as a graphics programmer, rewriting the rendering system is comparatively simple, enjoyable, and perhaps not worth 5% of a moderately successful game.

However, UE4 is much more than just a graphics library. I'd argue that it's editor alone is worth many times more than their rendering features. And IMO, it's trivially worth the 5% of revenue.

Writing a rendering system or this rendering system? I think you're underestimating the tech here. Could you match their real time global illumination, radiosity, physically based rendering, etc with good performance? I get the impression you'd need to go over like 100 different papers to even get a baseline implementation, without any clever optimizations, for a modern engine like UE4.

Yeah, any reasonably skilled programmer can write a pretty graphics engine as a hobby project, since that is the fun part of making an engine. It's all of the other boring stuff that is worth (arguably) more than 5%. Writing the resource management system and the editors takes a long time and a lot more effort and is not as fun or glamorous as writing a rendering engine.

Not to mention this is much more than a 3D rendering middleware.

Or, you know, pay the royalty you agreed to pay and stop being a thieving scum.

I would think they have some sort of enforcing mechanism. It almost seems like the $3,000 limit is a signal of the cutoff when it starts becoming worthwhile to pursue scum buckets.

Speaking as another developer, their terms sound incredibly fair.