diff --git a/ClassCreep.js b/ClassCreep.js
index 7e367d8..785bda4 100644
--- a/ClassCreep.js
+++ b/ClassCreep.js
@@ -4,5 +4,152 @@ module.exports = {
 
 class _Creep extends Creep {
 	init() {
+		if (this.memory.role == undefined) this.memory.role = ROLE_HARVESTER;
+		if (this.memory.recharge == undefined) this.memory.recharge = true;
+	}
+
+	toggleChargeMode() {
+		if (this.store.getFreeCapacity(RESOURCE_ENERGY) == 0) {
+			this.memory.recharge = false;
+		} else if (this.store.getUsedCapacity(RESOURCE_ENERGY) == 0) {
+			this.memory.recharge = true;
+		} else return;
+		this.memory.target = undefined;
+		this.memory.path = undefined;
+	}
+
+	findTarget(target) {
+		if (this.memory.target == undefined) {
+			this.memory.target = this.pos.findClosestByPath(target);
+			if (this.memory.target == null) {
+				this.memory.target = undefined;
+				return ERR_NOT_FOUND;
+			}
+		}
+		return OK;
+	}
+
+	findTarget(target, filter) {
+		if (this.memory.target == undefined) {
+			this.memory.target = this.pos.findClosestByPath(target, filter);
+			if (this.memory.target == null) {
+				this.memory.target = undefined;
+				return ERR_NOT_FOUND;
+			}
+		}
+		return OK;
+	}
+
+	harvestSource() {
+		if (this.findTarget(FIND_SOURCES) == ERR_NOT_FOUND) return;
+		const target = Game.getObjectById(this.memory.target.id);
+		if (this.moveToTarget() == OK) {
+			this.harvest(target);
+			this.toggleChargeMode();
+		}
+	}
+
+	harvesterJobs() {
+		if (this.memory.counter == undefined) this.memory.counter = 0;
+		switch (this.memory.counter % 4) {
+			case 0: this.supplyStructures();
+				break;
+			case 1: this.upgradeRoom();
+				break;
+			case 2: this.repairStructures();
+				break;
+			case 3: this.buildConstructionSites();
+				break;
+			default:
+				this.memory.counter++;
+				break;
+		}
+		if (this.memory.target == undefined) this.memory.counter++;
+	}
+
+	supplyStructures() {
+		if (this.findTarget(FIND_MY_STRUCTURES, {
+			filter: (s) => {
+				return s.structureType == STRUCTURE_SPAWN ||
+					s.structureType == STRUCTURE_EXTENSION ||
+					s.structureType == STRUCTURE_TOWER ||
+					s.structureType == STRUCTURE_STORAGE;
+			}
+		}) == ERR_NOT_FOUND) return;
+		const target = Game.getObjectById(this.memory.target.id);
+		if (this.moveToTarget() == OK) {
+			this.transfer(target, RESOURCE_ENERGY);
+			this.toggleChargeMode();
+		}
+	}
+
+	upgradeRoom() {
+		if (this.findTarget(FIND_MY_STRUCTURES, {
+			filter: (s) => {
+				return s.structureType == STRUCTURE_CONTROLLER;
+			}
+		}) == ERR_NOT_FOUND) return;
+		const target = Game.getObjectById(this.memory.target.id);
+		if (this.moveToTarget() == OK) {
+			this.upgradeController();
+			this.toggleChargeMode();
+		}
+	}
+
+	repairStructures() {
+		if (this.findTarget(FIND_MY_STRUCTURES, {
+			filter: (s) => {
+				return s.hits < s.hitsMax &&
+					s.structureType != STRUCTURE_WALL &&
+					s.structureType != STRUCTURE_RAMPART;
+			}
+		}) == ERR_NOT_FOUND);
+		if (this.findTarget(FIND_MY_STRUCTURES, {
+			filter: (s) => {
+				return s.hits < s.hitsMax;
+			}
+		}) == ERR_NOT_FOUND) return;
+
+		const target = Game.getObjectById(this.memory.target.id);
+		if (this.moveToTarget() == OK) {
+			this.repair(target);
+			this.toggleChargeMode();
+		}
+	}
+
+	buildConstructionSites() {
+		if (this.findTarget(FIND_MY_CONSTRUCTION_SITES) == ERR_NOT_FOUND) return;
+		const target = Game.getObjectById(this.memory.target.id);
+		if (this.moveToTarget() == OK) {
+			this.build(target);
+			this.toggleChargeMode();
+		}
+	}
+
+	// Moves to the target.
+	moveToTarget() {
+		if (this.pos.inRangeTo(this.memory.target.pos.x, this.memory.target.pos.y, 1)) {
+			this.memory.path = undefined;
+			return OK;
+		}
+		if (this.memory.path == undefined) {
+			var path = this.pos.findPathTo(this.memory.target.pos, {
+				ignoreCreeps: true, range: 1
+			});
+			path.reverse();
+			this.memory.path = path;
+		}
+		const step = this.memory.path.pop();
+		var response = this.move(step.direction);
+		if (response == OK) {
+			if (this.pos.x == step.x &&
+				this.pos.y == step.y) return ERR_BUSY;
+			response = this.moveTo(this.memory.target.pos.x, this.memory.target.pos.y);
+		}
+		if (response == OK || response == ERR_INVALID_ARGS || response == ERR_NOT_FOUND) {
+			this.memory.path = undefined;
+			return ERR_BUSY;
+		}
+		this.memory.path.push(step);
 	}
 }
diff --git a/ClassRoom.js b/ClassRoom.js
index 0f7c3a1..67fe4dd 100644
--- a/ClassRoom.js
+++ b/ClassRoom.js
@@ -13,6 +13,8 @@ class _Room extends Room {
 		if (this.controller.my && this.memory.state == ROOMSTATE_NEUTRAL) this.memory.state = ROOMSTATE_CAPITAL;
 	}
 
+	//#region Checks
+
 	// Is the level changed?
 	isNewLevel() {
 		if (this.memory.level == undefined) this.memory.level = -1;
@@ -21,7 +23,11 @@ class _Room extends Room {
 		return value;
 	}
 
+	// Is the max amount of construction sites achieved?
 	isConstructionQueueFull() { return this.find(FIND_CONSTRUCTION_SITES).length > 90; }
+	//#endregion
+
+	//#region Construcion
 
 	// Place construction sites for the road system.
 	planRoads() {
@@ -45,12 +51,18 @@ class _Room extends Room {
 			target_array[index++] = structure.pos;
 		});
 
-		// Also add all sources
+		// Add all sources to targets.
 		this.find(FIND_SOURCES).forEach(source => {
 			target_array[index++] = source.pos;
 		});
 
+		// Add minerals to targers
+		this.find(FIND_MINERALS).forEach(mineral => {
+			target_array[index++] = mineral.pos;
+		});
+
 		// Build a road for every permutation of the targets.
+		// TODO: When performance to high make this loop recoverable.
 		for (let i = 0; i < target_array.length; i++) {
 			const begin = target_array[i];
 			for (let j = 0; j < target_array.length; j++) {
@@ -72,4 +84,7 @@ class _Room extends Room {
 	planStructures() {
 
 	}
+
+	//#endregion
+
 }
diff --git a/ClassSpawn.js b/ClassSpawn.js
index e440a78..d43fb53 100644
--- a/ClassSpawn.js
+++ b/ClassSpawn.js
@@ -6,4 +6,32 @@ module.exports = {
 class _Spawn extends StructureSpawn {
 	init() {
 	}
+
+	requireNewCreep(role) {
+		const roleCount = this.room.find(FIND_MY_CREEPS, {
+			filter: (c) => { return c.memory.role == role; }
+		}).length;
+
+		switch (role) {
+			case ROLE_HARVESTER:
+				return roleCount < 5;
+				break;
+
+			default:
+				break;
+		}
+	}
+
+	createHarvester() {
+		var body = [WORK, CARRY, MOVE];
+		this.createCreep(body, "harvester", ROLE_HARVESTER);
+	}
+
+	createCreep(body, name, role) {
+		if (this.memory.creepCounter == undefined) this.memory.creepCounter = 0;
+		const response = this.spawnCreep(body, name + ": " + this.memory.creepCounter, {
+			memory: { role: role }
+		});
+		if (response == OK) this.memory.creepCounter++;
+	}
 }
diff --git a/_commands.js b/_commands.js
new file mode 100644
index 0000000..e69de29
diff --git a/_creeps.js b/_creeps.js
new file mode 100644
index 0000000..5b1afbf
--- /dev/null
+++ b/_creeps.js
@@ -0,0 +1,25 @@
+module.exports = {
+	// Gets called when recompiling and when Restart command is called.
+	start: function () {
+		for (const creep_name in Game.creeps) {
+			const creep = Game.creeps[creep_name];
+			creep.init();
+		}
+	},
+
+	// Gets called every tick.
+	update: function () {
+		for (const creep_name in Memory.creeps) {
+			const creep = Game.creeps[creep_name];
+			if (creep == undefined) delete Memory.creeps[creep_name];
+			switch (creep.memory.role) {
+				case ROLE_HARVESTER:
+					if (creep.memory.recharge) creep.harvestSource();
+					else creep.harvesterJobs();
+					break;
+				default:
+					break;
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/_roles.js b/_roles.js
deleted file mode 100644
index 8de96c7..0000000
--- a/_roles.js
+++ /dev/null
@@ -1,9 +0,0 @@
-module.exports = {
-	// Gets called when recompiling and when Restart command is called.
-	start: function () {
-	},
-
-	// Gets called every tick.
-	update: function () {
-	}
-}
\ No newline at end of file
diff --git a/_spawns.js b/_spawns.js
new file mode 100644
index 0000000..4fda0fd
--- /dev/null
+++ b/_spawns.js
@@ -0,0 +1,15 @@
+module.exports = {
+	start: function () {
+		for (const spawn_name in Game.spawns) {
+			const spawn = Game.spawns[spawn_name];
+			spawn.init();
+		}
+	},
+
+	update: function () {
+		for (const spawn_name in Game.spawns) {
+			const spawn = Game.spawns[spawn_name];
+			if (spawn.requireNewCreep(ROLE_HARVESTER)) spawn.createHarvester();
+		}
+	}
+}
\ No newline at end of file
diff --git a/_system.js b/_system.js
index d275fbd..4940eec 100644
--- a/_system.js
+++ b/_system.js
@@ -2,15 +2,21 @@
  * Basis of the entire system. Everything will be managed from here on out. 
 */
 const rooms = require("_rooms")
+const spawns = require("_spawns")
+const creeps = require("_creeps")
 
 module.exports = {
 	// Gets called when recompiling and when Restart command is called.
 	start: function () {
 		rooms.start();
+		spawns.start();
+		creeps.start();
 	},
 
 	// Gets called every tick.
 	update: function () {
 		rooms.update();
+		spawns.update();
+		creeps.update();
 	}
 }
diff --git a/main.js b/main.js
index 0955097..81a562d 100644
--- a/main.js
+++ b/main.js
@@ -41,4 +41,8 @@ function setConstants() {
     global.ROOMSTATE_CAPITAL = 1;
     global.ROOMSTATE_COLONY = 2;
     global.ROOMSTATE_OUTPOST = 3;
+
+    // The roles of creeps.
+    global.ROLE_HARVESTER = 0;
+
 }
\ No newline at end of file