Screeps http://www.screeps.com/

builder.js

module.exports = function (creep) {
	if(creep.energy == 0) {
		creep.moveTo(Game.spawns.Spawn1);
		Game.spawns.Spawn1.transferEnergy(creep);
	}
	else {
		var targets = creep.room.find(Game.CONSTRUCTION_SITES);
		if(targets.length) {
			creep.moveTo(targets[0]);
			creep.build(targets[0]);
		}
	}
}

guard.js

module.exports = function (creep) {
	var target = creep.pos.findNearest(Game.HOSTILE_CREEPS);
	if(target && creep.hits > creep.hitsMax - 500 /* no more attack */) {
		creep.moveTo(target);
		creep.attack(target);
	} else {
		creep.moveTo(Game.spawns.Spawn1);
	}
}

harvester.js

module.exports = function (creep) {
    if(creep.energy === creep.energyCapacity) {
	    creep.memory.source = null;
		creep.moveTo(Game.spawns.Spawn1);
		creep.transferEnergy(Game.spawns.Spawn1);
		return;
    }
    
    if (!creep.memory.source) {
        var sources = creep.room.find(Game.SOURCES_ACTIVE);
	    sources.sort(function(a, b) {
	        var aDeltaX = Math.abs(creep.pos.x - a.pos.x);
	        var aDeltaY = Math.abs(creep.pos.y - a.pos.y);
	        var aDelta = Math.sqrt(aDeltaX + aDeltaY);
	        
	        var bDeltaX = Math.abs(creep.pos.x - b.pos.x);
	        var bDeltaY = Math.abs(creep.pos.y - b.pos.y);
	        var bDelta = Math.sqrt(bDeltaX + bDeltaY);
	        
	        return aDelta < bDelta;
	    });
	    
	    var harvesters = creep.room.find(Game.MY_CREEPS, function(creep) {
	        return creep.memory.role === 'harvester';
	    });
	    var target = sources[0];
	    for (var i in sources) {
	        var count = 0;
	        for (var j in harvesters) {
	            if (harvesters[j].memory.source && 
	                    sources[i].pos.x === harvesters[j].memory.source.x && 
	                    sources[i].pos.y === harvesters[j].memory.source.y) {
	                count++;
	            }
	        }
	        if (count < 3) {
	            target = sources[i];
	        }
	    }
	    
	    creep.memory.source = {
	        id: target.id,
	        x: target.pos.x,
	        y:  target.pos.y
	        
	    }
    }
    
    creep.moveTo(creep.memory.source.x, creep.memory.source.y);
    var sources = creep.pos.findInRange(Game.SOURCES, 1);
    creep.harvest(sources[0]);
    
    if (sources[0] && sources[0].energy == 0) {
        creep.memory.source = null;
    }
}

healer.js

module.exports = function (creep) {
    var damagedCreep = creep.pos.findNearest(Game.MY_CREEPS, {
        filter: function(object) {
            return object !== creep && object.hits < object.hitsMax;
        }
    });
    if (creep.hits < creep.hitsMax - 100 /* no more heal */) {
    	creep.moveTo(Game.spawns.Spawn1);
    	creep.heal(damagedCreep);
    	return;
    }
    
    if(damagedCreep) {
    	creep.moveTo(damagedCreep);
    	creep.heal(damagedCreep);
    	return;
    }
    
    var guard = creep.pos.findNearest(Game.MY_CREEPS, {
        filter: function(creep) {
	        return creep.memory.role === 'guard';
        }
    });
    if (guard) {
    	creep.moveTo(guard);
    } else {
    	creep.moveTo(Game.spawns.Spawn1);
    	creep.heal(damagedCreep);
    }
}

main.js

var builder = require('builder');
var guard = require('guard');
var harvester = require('harvester');
var healer = require('healer');

var harvesters = [];
var guards = [];
var builders = [];
var healers = [];
for (var i in Game.creeps) {
    if(Game.creeps[i].memory.role == 'harvester') {
        harvesters.push(Game.creeps[i]);
    }
    if(Game.creeps[i].memory.role == 'guard') {
        guards.push(Game.creeps[i]);
    }
    if(Game.creeps[i].memory.role == 'builder') {
        builders.push(Game.creeps[i]);
    }
    if(Game.creeps[i].memory.role == 'healer') {
        healers.push(Game.creeps[i]);
    }
}

if(harvesters.length < 4) {
    Game.spawns.Spawn1.createCreep([Game.WORK, Game.CARRY, Game.MOVE], null, {role: 'harvester'});
} else {
    
    if ((guards.length + healers.length) / harvesters.length < 0.8) {
        if (guards.length < 1) {
            Game.spawns.Spawn1.createCreep([Game.TOUGH, Game.MOVE, Game.ATTACK, Game.MOVE, Game.ATTACK], null, {role: 'guard'});
        } else if (healers.length / guards.length < 0.5) {
            Game.spawns.Spawn1.createCreep([Game.HEAL, Game.MOVE], null, {role: 'healer'});
        } else {
            Game.spawns.Spawn1.createCreep([Game.TOUGH, Game.MOVE, Game.ATTACK, Game.MOVE, Game.ATTACK], null, {role: 'guard'});
        }
    } else {
        Game.spawns.Spawn1.createCreep([Game.WORK, Game.CARRY, Game.MOVE], null, {role: 'harvester'});
    }
}



/*if(harvesters.length < 3) {
    Game.spawns.Spawn1.createCreep([Game.WORK, Game.CARRY, Game.MOVE], null, {role: 'harvester'});
} else if(guards.length < 2) {
    Game.spawns.Spawn1.createCreep([Game.ATTACK, Game.ATTACK, Game.TOUGH, Game.MOVE, Game.MOVE], null, {role: 'guard'});
} else if(harvesters.length < 5) {
    Game.spawns.Spawn1.createCreep([Game.WORK, Game.CARRY, Game.MOVE], null, {role: 'harvester'});
} else if(healers.length < 1) {
    Game.spawns.Spawn1.createCreep([Game.HEAL, Game.TOUGH, Game.MOVE], null, {role: 'healer'});
} else if(guards.length < 3) {
    Game.spawns.Spawn1.createCreep([Game.ATTACK, Game.ATTACK, Game.TOUGH, Game.MOVE, Game.MOVE], null, {role: 'guard'});
} else if(guards.length < 6) {
    Game.spawns.Spawn1.createCreep([Game.ATTACK, Game.ATTACK, Game.TOUGH, Game.MOVE, Game.MOVE], null, {role: 'guard'});
}*/
    
    
/*} else if(builders.length < 1) {
    Game.spawns.Spawn1.createCreep([Game.WORK, Game.WORK, Game.CARRY, Game.MOVE], null, {role: 'builder'});
}*/


for(var name in Game.creeps) {
	var creep = Game.creeps[name];

	if(creep.memory.role == 'harvester') {
		harvester(creep);
	}

	if(creep.memory.role == 'builder') {
	    builder(creep);
	}
	
	if(creep.memory.role == 'guard') {
	    guard(creep);
    }
	
	if(creep.memory.role == 'healer') {
	    healer(creep);
    }
}