I am not afffiliated with C4 but I recommend it highly. I don't think any graphics engine in its price range ($350) offers one percent of the value you get for your money and that's not hyperbole; I've spent much more on other engines and mostly got nothing but disappointment and irritance. I usually don't post about stuff online either, but the licensing is changing so I thought I'd give a heads up in case anyone wanted to check it out before the new release comes.

Currently, you get free updates for life, which is pretty much unprecedented for an engine like this. After the new release the price is the same but there will be some kind of update fee every year or every two years, plus a 'basic' edition that costs less but has no source code included. I don't know the exact prices, but basically it will go to a structure similar to other similar engines where you pay for new updates after a certain point, which can be very expensive over the course of years.

So, if you're a serious gamemaking hobbyist or wouldbe professional it might be a good idea to give it a good looksee, or even pick up a license 'just in case' if you are one of those people who have had a game idea brewing for years on end that haven't quite gotten started with it yet. The graphics features and performance are comparable to many much more expensive engines, and it has all the tools you need to make most games out of the box, with easy hooks to put in middleware for things like physics or sound.

Unlike many engines, the author does everything himself. Many times an engine looks impressive until you see the author has basically glued together a bunch of middleware products which begs the question of whether or not they can actually do anything themselves at all once they run out of 3rd party APIs to throw in. It's also likely why the engine is rock solid stable. Many APIs (in my opinion) attempt to accelerate things which are not appropriate or necessary, and just lead to having to worry about poor driver support and OS issues. With multicore processing available it just doesn't make much sense to try to offload things like sound or GUI skinning to accelerators when it can be done on the CPU instead without having to make a round trip and rely on a dozen different driver implementations for various platforms.

Don't think this means the engine is slow, though. It seems to have performance comparable or better than many much more expensive engines out there, and I've always been surprised by just how much raw graphics firepower it has.

There's lots of editing tools available, including a voxel based terrain editor and a shader editor which is pretty nice. The editor tools are not as strong as some engines and don't compare well to say Unreal 3 editor, but they are simple to use and get the job done for most purposes. For a huge MMO they are not going to be enough yet, though, and there's no foliage system in place as yet either.

The current release has a homebrewed but impressive native physics implementation as the main thrust of development. With the addition of physics, C4 becomes a truly complete package for game making. The only game type you'd have issues making is an MMO due to the need for a huge world and the needed network support. However, there are a few projects that have implemented raknet and had much success in that department and world size capabilities are slated to increase in future releases.

The artwork in the demo is by and large not impressive, but if you have a bit of graphics knowledge and half a brain it's easy to see that the engine is great at rendering and the water effects and support for things like normal maps and parallax mapping is excellent as well. In fact, I get better accelerated rendering in C4 than I get in maya. Unless I drop down to mentalray it just doesn't ever display normal maps correctly but C4 automatically determines their format and makes sure there are no seams and rebuilds the object's normals if necessary. When you put in high quality artwork, the result is stunning, and in sheer looks it is very comparable to some of the big name engines that pump out the big name titles.

There's also a good community and great support and the APIs are easy to use. They do require C++ knowledge, but realistically speaking any game worth making will need that, and the required level to simply use the API is not very high at all and doesn't require professional C++ experience in the least. There's even a thread library which used a job queue which makes it very easy to make simple multithreaded code even if you don't have any multithreaded programming knowledge.

So again, not an advertisement, but a warning. If you might want to pick up a 3d engine some day then now's a good time to check it out or else you will be missing out on what's currently the best deal in the industry by far. Not sure when the new release will be done, but it's supposed to be any day now.

Oh, and the site is terathon.com. Just click around to find the demo.