The original LazerCatz bot!

lazer_bot.user.js

// ==UserScript==
// @name           Lazer Bot
// @author         jmhobbs
// @version        2.2
// @namespace      http://www.lazercatzthegame.com/
// @description    a bot for Lazer Catz
// @include        http://www.lazercatzthegame.com/*
// ==/UserScript==

var current_target = null;

function moveDude () {

	var potential = { id: null, distance: 4001, offset: [0,0] };

	for( var id in unsafeWindow.LC.players ) {
		if( id == unsafeWindow.LC.user.id ) { continue; } // Skip ourselves
		if( unsafeWindow.LC.players[id].dead ) { continue; } // Skip dead users
		var x_offset = unsafeWindow.LC.user.offset[0] - unsafeWindow.LC.players[id].offset[0],
		    y_offset = unsafeWindow.LC.user.offset[1] - unsafeWindow.LC.players[id].offset[1];
		var distance = Math.abs( x_offset ) + Math.abs( y_offset );
		if( potential.distance > distance ) {
			potential.id = id;
			potential.distance = distance;
			potential.offset = [ x_offset, y_offset ];
		}
	}

	if( potential.id == null ) {
		// Move randomly if no one is around
		var choices = [ 'n', 's', 'e', 'w' ];
		if( 1 == Math.floor( Math.random() * 2 ) ) {
			unsafeWindow.LC.moveUser( choices[Math.floor( Math.random() * 4 )] );
		}
		return setTimeout( moveDude, 500 );
	}

	if( current_target != potential.id ) {
		unsafeWindow.LC.message( "LazerBot Targeting " + unsafeWindow.LC.players[potential.id].nick );
		current_target = potential.id;
	}

	if( Math.abs( x_offset ) > Math.abs( y_offset ) ) {
		if( x_offset > 0 ) {
			if( x_offset > 40 ) {
				unsafeWindow.LC.moveUser( 'w' );
			}
			else {
				unsafeWindow.LC.moveUser( 'e' );
			}
		}
		else {
			if( x_offset < -40 ) {
				unsafeWindow.LC.moveUser( 'e' );
			}
			else {
				unsafeWindow.LC.moveUser( 'w' );
			}
		}
	}
	else {
		if( y_offset > 0 ) {
			if( y_offset > 40 ) {
				unsafeWindow.LC.moveUser( 'n' );
			}
			else {
				unsafeWindow.LC.moveUser( 's' );
			}
		}
		else {
			if( y_offset < -40 ) {
				unsafeWindow.LC.moveUser( 's ');
			}
			else {
				unsafeWindow.LC.moveUser( 'n ');
			}
		}
	}

	if( unsafeWindow.LC.user.charge >= 10 ) {
		unsafeWindow.LC.fire();
	}

	setTimeout( moveDude, 500 );
}

unsafeWindow.LC.startScreen.keyUp( { which: 13 } );
unsafeWindow.document.getElementById( "name-input" ).value = "LazerBot-" + Math.floor( Math.random() * 1000 );
unsafeWindow.LC.nameSelectScreen.keyUp( { which: 13 } );
unsafeWindow.LC.characterSelectScreen.keyUp( { which: 13 } );
unsafeWindow.LC.pew = { play: function () {} };
unsafeWindow.LC.message( "LazerBot Ready..." );
setTimeout( moveDude, 2500 );