Scratch

this is how to make a 1script 1sprite platformer (no velocity)

when green flag clicked:
forever:
if: (key (right) pressed)
change x by (5)

if: (key (left) pressed)
change x by (-5)

if: (key (up) pressed)
repeat (50) times:
change y by (1)
if: (key (left) pressed)
change x by (-5)
if: (key (right) pressed)
change x by (5)
if (not (touching color (color of platform)))
repeat until (touching (color of platform))
change y by  (5)
if: (key (left) pressed)
change x by (-5)
if: (key (right) pressed)
change x by (5)

if: (not (touching color (color of platform)))
repeat until (touching (color of platform))
change y by  (5)
if: (key (left) pressed)
change x by (-5)
if: (key (right) pressed)
change x by (5)


sorry if it is unclear.

if you want, here's a link:
http://scratch.mit.edu/projects/K-Jam/1686068