Minecraft style terrain engine in C# XNA 4.0, Microsoft Public License (Ms-PL).
Our own game project : Xenogalaxies
Proudly made by the techcraft team ( but Bamyazi is not involved any more, his new super cool job takes all his energy)
On indiegogo now : http://www.indiegogo.com/projects/xeno-galaxies

Other known games using this TechCraft engine:
Game : Zombie Block Planet
URL
http://marketplace.xbox.com/en-US/Product/Zombie-Block-Planet/66acd000-77fe-1000-9115-d80258550cda
Platform: XBOX 360
Game: Sunflower Farm
URL: http://www.tomlingames.com
Platform: XBOX360
Game: Miner4Ever
URL: http://www.runningpixel.com
Platform: XBOX360
Game: GunCraft
URL: http://www.kickstarter.com/projects/630555339/guncraft-voxel-based-first-person-shooter?ref=live
Platform: PC
Screenshot based on this repositories latest source code:
Crazy flowers and a dusting of snow:

Introduction
- We are not making a Minecraft clone but implementing an engine to learn the technology and as a base for new gameplays far away from Minecraft.
- The code was originally inspired from Infiniminer with lots of cleanups and optimisation. It runs on Windows and soon, the Xbox 360 and WP7.
Project Status
A progression of the core engine was done privately during the second half of 2011. It is likely that parts of this further engine update are added to this repository at an unconfirmed date in the near future. Please follow this project to receive notifications
of when the project is further updated.
Download
Download the latest version directly from the source tree :
http://techcraft.codeplex.com/SourceControl/list/changesets#
YouTube channel
We have a few demos of the engine as we develop. Found here:
http://www.youtube.com/jacootube
BamYazi also has a video of the experimental WP7 version here:
http://www.youtube.com/watch?v=VED0vThI4wQ
Images taken based on current source code:
Glowing flowers at dusk:

A colourful landscape under the stars at midnight:

The same view, at midday:

Realtime rippling, transparent water at midday:

Why make an opensource block Engine ?
Ever since Minecraft's success, there is so much design information and code samples available freely that keeping the source closed serves nothing: anyone serious about it can write such an engine, if investing enough time. And with projects like Minepackage
(Unity3d) and Infiniminer (XNA), the fox is in the hen house already!
So take the code and build something great (free or commercial, not our concern!), but please send us patches, discuss in the forums or fork it on the source code tab (we use mercurial). If you are using any part of the source code in other projects, free or
commercial, please mention TechCraft somewhere that the end players can see.