It has been long enough that this is probably unlawful thread necromancy, but I feel this thread has left the subject detrimental and may wane people from doing this which they could do in fear of legal action. I'm not a lawyer as anyone before, but I'm legally conscious. Laws are made to protect, not attack. You will never have a law suit that costs you money unless you terrorize, slander, or charge someone else money for something which you shouldn't have charged them for.
Using Construct 2 you will almost never have to fear someone attacking you for patent unless you rip off someone else's Construct 2 game. If you make a game just like Mario or Sonic, but implement all your own features, graphics, and orientation using Construct 2, you will be totally okay. In recent law, the obvious copycat Samsung Galaxy S3 tablet was under fire from the iPad3. Apple lost the case in the UK because tablets are now generic, and the two methods were considered different enough even though the intended market and goal were identical.
If you're using Trademark or characters in any way that isn't gaining you financial profit or slandering them, you will almost never have a law suit. If the owner of the Trademark decides to flex their muscles, they can order a seize and desist followed by court order if you don't follow through with their demands(and if they can find you-- if you upload your game to a web server like Scirra's site, they would get the seize and desist, and Scirra would undoubtedly comply and privately notify you what happened. If you don't take credit for your work, the credit falls onto the host). There may be literally a thousand Mario flash games on the internet which Nintendo could easily get rid of. The reason they still exist consistently and multiply is that it's flattering, good advertising, and cheaper for Nintendo to not hire someone to take care of it. If something graphic depicting Mario characters got in the news, they might do something about it, but System Every Tick-> 'noharm'='nofoul'. On this same subject, in my six degrees of separation table, I know a girl who was helping work with a guy that was making a Halo mod for Counter Strike Source. The intention was to take the Source Engine and make it as much like Halo as possible. Including that one of their members ripped the models and textures off of the Halo 2 disc and they were using the characters and vehicles as a part of their project. When the project got big, Microsoft ordered them to stop on account of the fact that they were making a game which could not be told apart from Halo 2 on a free engine and it could cut into future sales if there was a free version of it that you could get so long as you had the source engine on your computer. What this team was doing was an obvious ripoff, and months of work had been lost, but there was no lawsuit or financial damage.
Case in point, technically, a Trademark prevents you from blatantly using features from another company, but most of the time a big name company won't care unless you garner a serious amount of attention and you may be harmful. If I made a hack n' slash game, and then you made a hack n' slash game with my main character as one of the bosses, I would be flattered. I would be bothered, however, if that character was the selling point of the game, you were making money on it, and it wasn't discussed with me first. If I were a big name company and you were getting a lot of attention for my property, I would probably do something about it. Otherwise, knock your socks off! There's a lot of discretion involved with law, and not a whole lot someone can do to you financially if you're not making money.
My last big example(I promise) is South Park. They always request permission for their uses of celebrity names and media influences, and they don't always get it. Everyone knows what the episode of Chimpokomon was about, but it was in good parody(and not necessarily slanderous). Saying 'but yeah, everyone laughs at South Park', is not true. I don't laugh at South Park. I can see why anyone would find it offensive and not want to be involved with it. South Park makes a lot of money, and will make fun of whatever they want careful about what is legal and what isn't with the use of disclaimer. Parody is fair use, free to play games built around similar ideals is fair use, slander is not, ripping off hard work is not. There's a game on XBox Live Arcade called Angry Fish which is a shameless ripoff of you-know-what and costs a buck. It's still there. Sony's obvious Smash Brother's ripoff is the first Smash Brother's clone that's coming to America(!'thefirstmade') because in Japan Smash Brother's has been out long enough that it can legally be considered a genre now.
Chances are pretty slim that you won't run into the legal issue on pretty much any regard, but there are obvious reasons why you could. Being original on characters and art will pretty much keep you covered. Concepts are considered generic after you can name three games that do what you want. Small features that you take will go unnoticed to most people, and, most of all remember: to take ideas from one source is called plagiarism, but taking ideas from a group of people is called research!
Edit:I should note that this point is mostly American law, but internationally it seems to stand in most cases. the first example with the iPad and the Galaxy Tab is a funny one now that I checked my sources. The Galaxy Tab has been banned for sale in America, although Apple didn't win any money on it. It's legal to sell in the UK though, on account of the iPad "being cooler". Weird.Stercus2012-07-20 13:26:40