A lot of people seem to have a hard time coding a simple little gravity code for GM, while it's not recommended you use the default gravity functions, here is how it works.
if !place_meeting(x, y + 1, par_terrain) { gravity = 0.1; }else { if vspeed>0{ vspeed = 0; } gravity = 0; } if place_meeting(x,y,par_terrain){ y-=1; } By PVic