key_left = keyboard_check(vk_left);
key_right = keyboard_check(vk_right);
key_jump = keyboard_check_pressed(vk_space);

var move = key_right - key_left;
var onWall = place_meeting(x-5,y,oWall) - place_meeting(x+5,y,oWall);
var onGround = place_meeting(x,y+1,oWall);

mvtlock = max(mvtlock - 1, 0);

if (onWall != 0) vsp = min(vsp + 0.2, 3)
else vsp = vsp + grv;

I got the fully moving platformer with jumping, wall jump and wall slide done.

I used a reference for the movement, and this method of programming was really impressive since I've not done it before, but I was really excited to explain it to the nearest person to me, which sadly for him was lio

I am a god of programming

please don't force yourself to watch me program for 30 mins

but here's a video of me having to playtest and adjust the gravity settings combined with the wall slide for the whole time so I could get a good balance.