A really good attempt at PSX graphics.
Lacked luster and creativity for me as true at it was to catch the train it felt like a walking simulator.
A lot of things felt out of the place like grass.png or the default godot sky
Did not have a creative edge on the theme given the time frame of 7 days
as for some tips I would say focus on visuals too.
Best way to do it is having a check list of essentials like sky etc
Don't oversimplify your game
Good potential