You can access the source code to unreal engine when you get a license, but the terms are not by any stretch of the imagination open source. You wouldn't be able to freely share your modifications for instance.

You don't have to get a "license" (at least in the sense of paying anything), IIRC you just connect your EGS account to your Github account, accept an EULA (which technically is a "license" I guess) and then have read access to the Unreal Engine GH repositories.

(currently there seem to be around half a million users with access)

What do you think clicking the EULA is?

I'm hailing from the ancient times where getting a "game engine license" involved several in-person meetings both between top-level management followed by engineers, followed by exhaustive due diligence from both sides, intense haggling for several months, and finally signing a proper "contract", handing over absurd amounts of money upfront and then paying royalties after release.

That's basically what I understand as "getting a license", OTH I accept probably 5..10 EULAs a week without thinking or even reading the text (most of them are not enforceable anyway).

"Clicking EULA" might not be enforceable in many countries.

Like which?

AFAIK in Germany the TL;DR is that if there's anything in the EULA which violates "German Civil Code (BGB)", then either parts or all of the EULA are invalid. I remember that in Germany an EULA cannot prohibit reselling the software to somebody else, or making your own backup copy (kinda tricky nowadays though where everything is just a "service").

"AFAIK in Germany the TL;DR is that if there's anything in the EULA which violates "German Civil Code (BGB)", then either parts or all of the EULA are invalid. "

There is nothing unique about German law here. The same is true in the USA and most other countries. If a EULA or any other contract (whether agreed verbally, signed physically, digitally, or via a "click") violates the law, it can be considered invalid/unenforceable. It has nothing to do with how the agreement was agreed to, but with what the agreement contains. (There may be some legal theory that may carry some weight that a contract agreed to via a "click" is more likely to be unconscionable that one agreed to with a physical signature, but that does not automatically make all "click" agreements unenforceable.)

There are multiple reasons why an EULA may be viewed as unenforceable in the EU due to unfair terms: https://europa.eu/youreurope/citizens/consumers/unfair-treat...

Interestingly, Unity runs afoul of many of those.

That's just standard contract law in any country.

In which case you have no license to the code. So either way, you'd have no rights.

You're still welcome to contact them directly and try to get some kind of contract directly if you can't agree to the EULA for access.

That's still not open source. Try cloning their repo and making it public.

> when you get a license

I was going to comment that it’s viewable by anyone on their GitHub, but you are correct: you have to be part of the Epic GitHub organisation to access the repo. Getting access is easy, but you do have to agree to their licensing terms to do so. So yes, what you said.

> You wouldn't be able to freely share your modifications for instance.

Have you read the unreal engine license agreement? [0]. Section 3.a covers modifications

[0] https://www.unrealengine.com/en-US/eula/unreal

Section 3.a covers products you’ve made with the licensed technology. I don’t see any language about modifications to the licensed technology.

Edit: I see some language covering this further up.

I used to work for Epic so I have some inside knowledge, but modifying the engine and sharing it with other licensees (via the UDN forum usually) Its actively encouraged too.

Unreal is source available