These are some of the general game mechanics that will be seen in Medieval Engineers.
The terrain is generated procedurally, which is to say it generates randomly, but follows certain rules. This results in a nearly infinite number of unique worlds for players to experience. The generation is based on a "seed" which can be shared to allow others to experience an identical world.
All game objects will have their integrity determined based upon their mass and structure. As shown in recent videos and interviews, in creative mode players have access to a debug menu which allows seeing a stress value placed upon each block. Furthermore, blocks get highlighted red when they are about to collapse.
Structural integrity is a core concept to medieval engineers and requires a more thoughtful approach to building than games up to this point have required. Weak bridges can break from simply having a player walk over them and stronger ones still may not be able to handle a cart laden with supplies unless realistic precautions and building techniques are used. The integrity of structures is especially important for combat, as weaker structures are far more prone to destruction, and may have weak points that will destroy it much faster. It appears that an accurate trebuchet or other form of weponry will be quite important as you can reduce a wall to rubble significantly faster by grouping shots and targeting weak points.
The voxel hand is the tool provided for players to make terrain alterations.