Ok so to play this game, what you are going to want to do is copy the text below:

##################
#%              %#
#%              %#
##              ##
##              ##
##              ##
##              ##
#P               #
####          ####
#  #          #  #
#  #          ####
####   !  !   #  #
#  #          ####
#  #          #  #
#  #   !  !   #  #
#  #          ####
####          #  #
#  #   !  !   ####
#  #   #  #   #  #
##################

P = Player
# = Brick
? = QuestionBrick
% = Box
X = Dedly
! = Spring
. = JumpingSpring

// List syntax
ThingsThatFall = [ Player JumpingSpring ]

Sproingy = [ Spring JumpingSpring ]

// Accelerate down, like gravity. On everything in the list
{ ThingsThatFall } -> { DOWN ThingsThatFall }

// Move sideways with <LEFT> and <RIGHT> arrow keys
{ <HORIZONTAL> Player } -> { HORIZONTAL Player }

// Move up while pressing against a wall
HORIZONTAL { Player | Wall } -> { UP Player | Wall }

// Springs are Sproingy
DOWN { DOWN ThingsThatFall | Sproingy } -> { JUMP ThingsThatFall | JUMP JumpingSpring }
DOWN { DOWN JumpingSpring | Wall } -> { JUMP JumpingSpring | Wall }

// Player dies if touching Dedlies
{ Player | Dedly } -> { DEAD Player | Dedly }

// Win if touch box
{ Player | Box } -> { WIN Player | Box }

And paste it into here: https://waynetron.github.io/micro-gg/

And then click the "play" button on the top-right.

micro gg is the work of @WaynePetzler. Here's the tweet that made me find out about it.