Adventure Game Studio vs ShiVa

Good for newbie game creators. Can be used for prototyping: on several occasions was used to make a demo/experimental version before creating a final commercial product on different engine.

AGS is licensed under Artistic License 2.0 and is completely free for use for creating both freeware and commercial games.

Besides the manual there are multiple text and video tutorials and code samples written by community.

Adventure Game Studio has been used to develop games such as "Resonance", "Blackwell" series, "Gemini Rue", "Primordia".

An extensive library of game templates and script modules accumulated over years. You can construct a simple game in hours (if you know what you are doing).

An old, big and active community which would support newcomers not only in learning basics of the engine, but can help with every aspect of game making (including art, voice acting, moral support, etc).

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.