A simple game played entirely in audio. For best effect, play with headphones on and eyes shut :)

/*
* KEEPY-UPPY
*
* To run this game, select all the text and press the SuperCollider key for execute-code (on Mac it's Enter).
*
* An AUDIO game written in SuperCollider by Dan Stowell (C) 2005
* Released under the GNU Public Licence
* See http://www.gnu.org/copyleft/gpl.html for licence details
*
* This game is based on being told about the work of "One Switch"
* http://www.oneswitch.org.uk/ - developing games and controllers
* to accommodate various types of disability, including...
* audio-only games.
*
* RULES:
*  You are kicking a football into the air. You can hear it fly 
*  up into the air and down again, and when it comes down you 
*  must press SPACE to kick it up again.
*
*  The ball may move slightly towards the left or right so you
*  may need to move left or right using the cursor keys to 
*  keep within range of the ball (wear headphones for best 
*  control!)
*
*  The aim is to kick it up as many times as you can.
*
*
*/

(
s.waitForBoot{
	Task{
		
		// Then send it the SynthDefs we need
		(
			SynthDef(\kuball, { |amp=0.5, pan=0, freq=100|
				Out.ar(0, Pan2.ar(amp * 2 *(BPF.ar(WhiteNoise.ar, freq, 0.1)*10).clip2 * SinOsc.ar(4.5), pan))
			}).send(s);
			
			SynthDef(\gameover, { Out.ar(0, SinOsc.ar(
				Line.kr(200, 100, 1.0, doneAction:0),
				0,
				EnvGen.kr(Env([0.3, 0.2, 0.2, 0], [0.1, 0.8, 0.1]), 1, doneAction:2)
			).dup(2))}).send(s);
			
			SynthDef(\whackit, {Out.ar(0, SinOsc.ar(74, 0.5pi, 
				EnvGen.kr(Env.perc(0, 0.05), doneAction:2)).dup(2))}).send(s);
			
		);
		0.1.wait;
		s.sync;
		
		// Now define the game
		(
			~announce = Platform.case(
				\osx, {{|msg| msg.speak}},
				\linux, {{|msg| msg.speak}},
				\windows, {{|msg| msg.postln}}
			);
			
			~game = {
				
				var whacks, xpos, ypos, xvel, yvel, whack, dogravity, framedur, doc, whackdisabled, whackspacing;
				
				
				whacks = 0;
				xpos   = 0;
				ypos   = 0;
				xvel   = 0;
				yvel   = 10;
				framedur = 0.1; // The amount of time between two "frames" of calculation
				whackdisabled = false;
				whackspacing = 0.3; // The amount of time you must wait between whacks 
				
				whack = {
					if(ypos < 20,
						{
							if(xpos.abs < 1,
								{
									if((yvel < 0) && (whackdisabled==false),
										{
											yvel = rrand(6.0, 14.0);
											ypos = max(0.1, ypos);
											xvel = 0.1.bilinrand;
											Synth(\whackit);
											whackdisabled = true;
											Task({whackspacing.wait; whackdisabled = false}).play;
											whacks = whacks + 1;
											//doc.string="WHACK!";
									});
								},
								{
									//doc.string="Missed!";
							});
						}, 
						{
							//doc.string="The ball is too high to hit";
					});
				}; // End of whack function
				
				dogravity = {
					yvel = yvel - 1.0;
					ypos = ypos + yvel;
					xpos = xpos + xvel;
				};
				
				Task({
					var kuball;
					
					kuball = Synth(\kuball);
					
					// Set up keyboard handlers
					AppClock.sched(0.0, {
						//doc = Document.new("Use LEFT and RIGHT arrows and SPACEBAR", "");
						doc = GUI.window.new("Use LEFT and RIGHT arrows and SPACEBAR");
						doc.front;
						doc.view.keyDownAction_({arg ...args;
							switch(args[3],
								32   , {whack.value}, // space
								63234, {xpos = xpos + 0.1}, // left arrow
								63235, {xpos = xpos - 0.1} // right arrow
							);
						});
					});
					0.1.wait;
					
					// This is the loop which runs the game
					while({ypos >= 0},
						{
							dogravity.value;
							kuball.set(\amp, 0.5 * (1.0/max(1.0, ypos)), 
								\pan, max(-1.0, min(1.0, xpos)), 
								\freq, 200 + max(0, ypos * 10));
							framedur.wait;
					});
					
					// Destroy keyboard handlers
					AppClock.sched(0, {
						doc.view.keyDownAction_(nil);
					});
					kuball.free;
					
					// Run the end-of-game feedback etc
					Synth(\gameover);
					1.5.wait;
					AppClock.sched(0.0, {doc.close;});
					switch(whacks,
						0, {~announce.("You didn't hit the ball - sorry");}, 
						1, {~announce.("You hit the ball once");},
						2, {~announce.("You hit the ball twice");},
						3, {~announce.("You hit the ball 3 times");},
						4, {~announce.("You hit the ball 4 times - well done");},
						5, {~announce.("You hit the ball 5 times - well done");},
						{~announce.("You hit the ball "+whacks+" times - well done indeed!");}
					);
					
				}).play;
				
				
			}
		);
		~game.value; // Press Enter to play!
	}.play
}
)