I've recently been working with Unity Technologies
Unity3d game engine. Unity is attractive as the basic version is free to download and use, and the editor pretty easy to get to grips with (although I admit to struggling to master camera control). Its great strengths are a graphically stunning 3d engine and the ability to compile the same basic level for delivery as a standalone file for a range of platforms or via a web-browser plug-in. Since this is a stripped back game engine, not hung on a particular game, the combat element that is so hard to get around in CryEngine is wholly absent, a refreshing change.
Unity appears to work well with greyscale heightmaps for defining real-world terrain (although confusingly the editor appears to mirror the x and y co-ordinates of the original image) and there are a range of pre-fab objects and textures to make level creation possible straight from the box, so to speak. I'm impressed and so will be working to get to grips with the finer points of Unity in the hope that it may provide a better solution than my favourite, CryEngine, in the longer term.
