Source vs NeoAxis Engine

Valve's official documentation website is great for newbies. It demonstrates the pros and cons of the engine (and since the website isn't maintained by Valve, but instead the community, the pros and cons are largely unbiased). There are also a number of pages dedicated to entities used within official Valve games and also community-made mods that were turned into full-fledged games by Valve. These pages explain the ins and outs of how most source programming works. There are also guides for Valve's tools which are both included in Source SDK and in any Valve-developed game.

Since it has precalculated lighting, this engine is great for low end PCs too.

You don't need to code your own door or ladder etc. You can pretty much use every entity used in Half-Life 2 yourself easily.

Of course you can program stuff into source but for level design only, source has a really easy input/output system for your level logic (e.g. doors, trigger when player walks into room...).

Source includes Source Filmmaker, a video capture and editing application.

You can use the engine for any commercial products and keep all the profits since NeoAxis does not ask for any royalties.

You can learn how to use Neoaxis in a few days.

You can easily create maps/scenes and add custom objects with physics and animations in a few minutes.

Has about 30 built-in maps with different game modes which can be opened by the map editor and their source code can be edited.

Supports Visual Studio, SharpDevelop or MonoDevelop.