I think the general argument in favour of UE4 Is pretty well founded. It's a good engine, and the Blueprints system seems to be meshing well with non-programmers.
I would encourage investing some initial time in familiarising the participants with the fundamentals of programming (in this case, visual programming) in order to enabe them to embrace the mindset that is required to problem-solve with programming tools.
In the interests of being open, there is also the Blender Game Engine. It has a some-what restrictive visual programming tool called "Logic Bricks". It has a quasi-nodal interface, with the restriction that there are three columns for sensors, controllers and actuators, and each may only trigger left to right. Essentially it's a source - evaluation - action system.
It is possible to run Python as a controller if more advanced evaluation is required (or use an Expression controller which allows basic boolean operators and property (attribute) comparisons).
The biggest benefit of the engine is that it is embedded inside of Blender, a 3D modelling, animation, rendering, simulation, compositing ... program, which means it is very quick to import models, textures and other materials into the game, and no code nor export pipeline is required.