It looks good but a bit too simplistic. You have around 6 colours being (grey, light green, dark green, red yellow/bage and dark grey/blue). It reminds me of a tutorial level in one of my 3DS max books which also uses a mental hospital. Maybe try and balance out some of the colours by adding in maybe a rusted out car or…
i suggest doing something more to the scene to make it pop... especially from the far away shots it feels boring and lacks props and such what may make a big difference is the grass, instead of having it all overgrown and thick - try the patchy look, example would be this screenshot you took: i find it much more visually…
I'd say the cold, grey lighting from your first examples is a bit better, but could still use some work. E.G. Upped the contrast, sucked out much of the red, green and blue saturation (from the perspective of Photoshop's Hue/Saturation tool).