I wanted to know if with this plugin you can create a game similar to Minecraft :
1) A map (cubes) randomly generated
2) Save / load your current game
3) Destroy the cubes
6) AI of the enemies
Is this project hard?
It depends on how much knowledge you have on the eventing system in Construct 2 and the Q3D plugin.
Let me reply to you in the same steps you asked...
1) Do you have knowledge on Arrays? You need to be able to link it with the XYZ-axis, adjust the coordinates, and also; How big do you want to make your game? Do you have modeling/ texturing knowledge?
2) There is a save/ load system in Construct 2, but you'll need to edit it to make it work with the array system.
3) Make the 3d object in the array part of a family and make sure every different kind of block has different ID's(using family variables?) so you will be able do destroy an individual block from a family by using conditionals.
4) Arrays, Variables, Link a database to each item in the array. Arrayception ;P
5) Conditions using Arrays.
6) Use on overlap, or compare 2 values conditionals, etc...
In my opinion I can tell you it's easier to make a Minecraft like game in Construct 2 than in Unity.
But I don't recommend doing this if you are a beginner, as you would also need to edit the renderer to make the game perform well(which is hard to do). Unlimited land generation with collision detection and things like that is very heavy on your CPU, so keep that in mind.
This would also take a long time to make, considering the time it took developing Minecraft, and perfecting it.
I already struggle with making my models and textures work after importing them to Construct 2, even though I correctly have imported the files being sure they're linked well together.
Final answer, do not let this stop you, but hold off on beginning with a project like this until you have a lot of experience using a lot of different behaviors in Construct 2, because this will test your knowledge and patience.