Thanks for the comments.
@ eggfruit, yes the version in my artstation portfolio is a bit brighter, I changed it after receiving some comments.

@ both of you. Concerning the yellow beam, I'll probably do some test to make it a bit smaller. I had a version where the yellow painting on the floor was a bit more clean and bright, but I didn't like it as much as this version.
Yes some trike were place in between areas of light.
I am pretty happy with the rendering quality of Mantra. The principle shader in Houdini is very easy to work with, plugging textures coming from Substance Painter is quick and painless. I am bit suprised by the rendering speed off Mantra, which I find a bit slow, this 1080p image took 4 hours to render and I am currently rendering a 4k version which will take around 15h. I am sure once I will have learn more tricks on how to optimize Mantra, it will go down a bit.
I might have made a mistake with the spelling of Trike , my native tongue is not english. But doing a quick search in wikipedia say that Tryke refers to Tricycle, so maybe it's ok then. Not sure anymore.