I have created a very simple card game but I am worried some of the mechanics may be shared with others. Is there anywhere I can check this, and what would be the outcome if other games did share the mechanic?
Note: I Am Not A Lawyer, this is mostly just accumulated internet knowledge, and may be inaccurate.
Card game mechanics are patentable. This means your mechanics could be already be patented by another company.
A patent protects a unique invention or process. It protects it by preventing someone else from duplicating your invention/process for a period of time (typically 20 years).
Yes, Richard Garfield patented tapping. The patent, by my reading, runs out on June 22 of this year (2014). Wizards went back and tacked on some other parts to that same patent, which you can read here. The patent covers just about everything you could imagine in a TCG. It covers building decks, casting spells, the process of trading with others and more.
Wizards is saying that Hex violates a lot of its patents. Hex probably does. Here’s the problem:
Those patent claims are beatable.
For example, they might be too abstract. They might be too broad. Having a patent does not guarantee that it will be valid in the face of someone challenging it. And importantly, if they run out when I think they will, Hex/Crypto can limit the damages they pay out to only the infringing time. After that, Hex isn’t infringing on any sort of patents held by Wizards. They’re probably still infringing on all the patents that early adopters lined up on the internet regarding downloads, backups, dropboxes and other horror stories. Litigating patents takes an incredible amount of money, especially when you’re trying to get it declared invalid one way or another.
While your game is in development/playtesting, this is not a big deal, as you're not charging money, and so the worst you could expect would be to be told to stop.*
Once that changes and you're actually trying to charge for this stuff, you should seek actual professional paid-for advice. Apart from anything else, you should consult a lawyer about starting a company to control the game, so that in the event of lawsuits or contracts, only the assets of the company will be liable.
*: Warning: I may be completely wrong about this.
Google has a way to search for patents. https://www.google.ca/?tbm=pts&gws_rd=cr,ssl&ei=92GlVb5Jwct6juip0Aw
But as mentioned before, professional help might be the best. When it comes to things of a legal nature, don't assume you know the answers. Do what you do best and rely on others to do their thing.
As a side piece (which could be useful to @deworde), there's a difference between a sole-proprietor and incorporation for a company, which comes with different legal protections and obligations. Make sure you speak to a proper lawyer before making major decisions like these. :)
It's actually unclear if game mechanics are still patent eligible in the US after the 2013 Alice ruling. (Game mechanics have traditionally been protected by patent, but now there is a question as to whether they are "abstract" and therefore not patentable. If this is the case, it probably violates the "spirit" of US intellectual property law, because if game mechanics are no longer patentable, there is no intellectual property protection for games, in that all game are abstract--artwork and characters, which are protected by copyright, are artistic elements, and do not constitute game IP.)
I'd have to do more research on the Hex/WOC case, although if the patent itself wasn't challenged and overturned, that's a good sign for game developer in general. (i.e. it means if you develop truly novel mechanics, and patent them, they can be indiscriminately stolen by cloners as in the case of the 2048 puzzle.)
The underlying issue you bring up is indeed a problem.
When I was preparing to patent my own set of completely novel game mechanics, I did exhaustive searches for similar games. In my case, no such games existed, but that is a factor of an entirely novel set of core mechanics, which isn't the condition for card games.
The other problem is the popularity of card games--there are so many of them!
However, any mechanics that are in the public domain, either because they were made public before seeking patent protection (with a minor caveat of a 1 year grace period) or because the patent expired, as with Magic the Gathering, can be freely used.
You can restrict your search of card game mechanics only to patent documents, which significantly narrows your search
If you don't find the mechanics in an granted patent that is still within the 2 year protection term, or a patent application still waiting for review, there shouldn't be a problem.