Android: Netrunner was a great cyberpunk-themed, asymmetrical card game which ran 2012-2018, and ended because of a licensing disagreement between FFG and WotC.
Null Signal Games is a donation and volunteer-driven organization which has been shepherding the game - designing new sets, commissioning artists, providing prize kits, and organizing big events to let the game continue. For the most part, they've been knocking it out of the park. New cards are freely available as print-and-play files. Proxying is allowed and encouraged.
Just to not give a purely rosy picture, I'll note that they foster a very combative social justice element which drove some heavy-handed choices and sour community interactions, but on the whole it's been a laudable effort, and continues to do great work.
This is also true of WotC.
To give one example - Netrunner has (had, I guess) a mechanic called Brain Damage, tied to effects which in lore terms did just that to the runner (hacker) character: heavily damaged by nasty corp tech while jacked into the cyberspace, and having to operate with less capacity/limited resources from that point on. Pretty standard cyberpunk stuff.
Null Signal decided one day that the term is grossly insensitive and now purged from the game, and while they might've told you to print cards containing it up until yesterday, reading it off your cards is now considered literal violence and will get you booted off tournaments. If you're not immediately 100% on board with this decision, you are a morally deficient person and not welcome in the community.
"You will not be banned for referring to brain damage. We prefer that you switch to core damage, and will remind you, but it’s not an enumerated infraction.
However, if a fellow player is harmed by any aspect of your behavior (including using the old term instead of the new term) and politely requests that you stop, you are expected to do so. We have always asked players to be polite and make easy accommodations when asked, as is clarified by our Code of Conduct. This is not a change in policy."
That Reddit thread is here. It seems to have been thoroughly cleaned up, but you can still see some slivers. I don't think it's worth wading through it, especially if Null Signal learned to be more diplomatic from it - just wanted to make it clear that I was being truthful, or at least as best as I could. I remember the "violence" and "morally deficient" bits as direct quotes, but my memory might be faulty and hyperbolized.
https://www.reddit.com/r/Netrunner/comments/vvr25h/nisei_an_...
(NISEI is the former name of Null Signal Games, that's also a term they deemed insensitive, and chose to fully rebrand.)
I'm very interested in seeing how Null Signal progresses. The LCG community has always had problems with gaining new members. A new game would launch, tons of people pick up the core sets. The games get into their first few cycles, and then no new people start to join. Then another LCG would come out, and people would go play the new hotness. I don't know if Null Signal is trying to overcome this problem though.
I did find it interesting that WotC has seemingly abandoned their Netrunner trademark [0]. I wonder if that means they Null Signal is effectively in the free in clear. They always seemed to be operating in a bit of a grey area. I don't have a lawyer friend who I've been able to ask.
In this same vein, Pinebox Entertainment [1] has been keeping AEG's Doomtown: Reloaded alive in a similar way. Another fantastic "LCG"* that a big company quit supporting but was picked up a by another small group. Neither of these games have a big following, but I'm interested if either of them will make an economically viable competitive LCG game. As it stands, FFG and AEG have abandoned all of their competitive FFGs. And FFG had several. Only their cooperative LCGs remain.
[0]: https://uspto.report/TM/90791419
[1]: https://pineboxentertainment.com/
* I say "LCG" because that was a trademarked term by FFG. AEG wasn't allowed to call it LCG. I forget what they called it. But it had an identical distribution model.
I'm currently a very happy player of Flesh and Blood TCG and think it's a fantastic game with great stewardship, but I have very mixed feelings about game economy entirely based on boosters, especially now that I work on games myself.
I realised that all it would take to make a community version of Magic would be to change all the parts of ability text that are IP in my grammar [3]. For example "tapping", "kavu", "merfolk" and "phyrexian mana" would be out. But other than that, about 60% of the game could be basically replicated. That's 60% because it was just a degree project and so incomplete (e.g. Planeswalkers had just come out and they weren't implemented).
Alternatively the entire engine and its language could be re-written from scratch, though that would take a lot more work.
As to having actual cards to play with, I thought it would be a great idea to let the players make their own cards, just like many casual players make their own proxies of published cards. That would add a creative element to the hobby, similar to modelling in Warhammer games, that I thought would make it into something entirely new.
Suffice it to say, after my degree I never had the time to actively pursue this. But I still think it's perfectly possible.
Edit: just to be clear, the reason why it's interesting to have a generator for rules text is that you can generate, and validate, new cards automagickally. Then you can let the players script their own cards and validate them against the parser. So the entire game is completely decentralised with the only authority being the parser (and its maintenance team). Game balance is a problem but that, too, can be dealt with by tweaking the parser so it won't generate or accept imba cards.
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[1] M:tG Arena uses the same idea today, but that was back in 2011. To clarify, the idea is that the ability text on cards is parsed and interpreted just like a scripting language. The interpreter, then, is the rules engine. The alternative is to code each individual card separately, which was done by earlier systems but is complete madness given the thousands of M:tG cards that have to be treated this way.
[2] Prolog programs can be "run backwards" under some conditions, so a parser is also a generator.
[3] Again this was in Prolog so the grammar was the parser. Definite Clause Grammars are syntactic sugar for Prolog so they're executable as any Prolog program. So you write a grammar, you have a parser, and it's also a generator.
Actually cloning the rules isn't the issue. Convincing the community to use your off-brand version is the issue, and trying to keep the community together in the absence of the trusted central authority of the company producing the game. That can't be easily replicated.
Consider Wargaming: Every tabletop wargamer I know eventually designs their own rule system. Yet none of them can displace Warhammer 40k, despite 40k's rules not even being very good in the first place and GW frequently alienating fans.
But, I know how to write code, not how to make people follow me in my hare-brained schemes :)
>> All very cool stuff (awesome to see serious work done in Prolog!) but...
There's plenty of serious work done in Prolog. My new job is maintaining a 30-year old behemoth of a Prolog project used to manage company car rentals. I'd never heard of it before starting to work with it and I'm betting there's plenty more where it came from.