Source vs ShiVa

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.

The free ShiVa Web version is limited to web publication, but otherwise has the same capabilities as the $200 ShiVa Basic. Upgrading to the $1000 ShiVa Advanced brings tools geared toward team development and professional releases, such as integrated SVN support and profiling tools. All versions are royalty-free.

All game logic can be scripted in Lua. ShiVa also provides a cross-compiler from Lua to C++, allowing Lua scripts to be further optimized and compiled to native code for performance.

In addition to the help forum, Basic and Advanced licensees have chat and direct email access to the developers.

Smaller platform specific executables, native code export, good FPS even for complex scenes. ShiVa has great advanced optimization features, including PVS and LOD, decreasing number of drawcalls even in complex level. Platform specific profiles allow developers to customize size and compression level for textures and test those settings directly in editor. Other engine features, like lightning baking, mesh combining and GPU skinning will boost performance too.