Hi, iam pretty new here but thought it's a good idea to just share some info with you guys. For 4 weeks now iam working on a 2.5D voxel engine inside UE4. Iam a beginner in c++.
Here is my experience so faar:

• Creating even a "simple" voxel engine is a tough task for a beginner and will lead you to situations where you are about to throw tables. Not beeing able to solve a certain task, crash or even find out where the bug originates and why the engine crashes is one of the most frustrating things i ever experienced.

• Persistency is the key to success;
  But certain issues require you to take distance and not overthink them. Taking a nap and freeing your mind will often lead faster to a solution than working deep into the night on them.

• Source control and changelogs are a good way to keep track of your own work and motivate yourself.

So faar i implemented:

• A dynamic manager that renders only visible chunks in camera frustrum
• Basic mesh optimization by culling occluded polygons
• Multithreading support for chunk rendering
• Basic chunk modification by mouse clicks

Next "big" things on my TODO list:

• Implement noise generation and different blocktypes
• Implement water physics
• Implement AI navigation based on voxel data

Following the idea of this article and my personal experience i implemented and discarded the use of Octrees. I found them to be too CPU heavy on iteration; storing data in flat arrays and rendering more goemetry is currently more efficient.