1080p.
I set the system resolution to 720p and the game never dropped below 30fps on the first level, mostly of the time at 35~45 fps.
In the second level it was below 30fps. Mostly of the time about 20 fps.
I’m pretty sure it would run fine (30 fps, 720p (if you write a resolution slider)) with 4 gb ram, similar CPU, and a dedicated GPU with 1 gb vram.