Spore’s first true expansion pack--and we’re not counting the weak Creepy & Cute, an assortment of extra body parts--fundamentally changes the game. In the original Spore’s final stage, you’re bound to a spaceship, but Galactic Adventures lets you park on planets and stretch your legs. These away missions beget a whole new universe of gameplay, including combat-based action sequences and story-driven adventures heretofore unseen in Spore. Unfortunately, the quality of these tweaks is just as open-ended, often resulting in frustration and untapped potential.

Like the millions of creatures that can inhabit your game, these new intraplanetary missions are largely created by other players. Galactic Adventures includes fairly understandable tools to script these sessions, and the tutorial does a good job of explaining the basics.

Just don’t expect adventures to congeal as easily as sticking legs on a creature and watching as the game makes it dance. In fact, crafting an enjoyable adventure that lasts just a few minutes can require hours of work on your part. At the very least, you’ll write all of the dialogue and events and pick all of the objects and characters from Spore’s huge catalog.

In a Robot Chicken story, you've got to conquer a malfunctioning intergalactic rest stop.

A simple checkpoint system lets you advance as a player by killing or befriending another creature, bringing two objects together (such as a key to a gate), or otherwise interacting with your story. Layer small events like these together, and you can create complicated adventures--although they all result in linear stories.

Still, you can personally craft nearly everything in the game: individual creatures, planetary environments, background music, ambient structures, building interiors, and more. If you have the time and creativity, Galactic Adventures can generate astonishing, unique results.

But at what cost? As a player in other people’s sandboxes, you’ll encounter many more first-draft worlds than masterpieces. Theoretically, a ranking system should help you find crowd-approved favorites, but weak organization somehow doesn’t bring the best to the top.

Spore’s developers built in a few dozen adventures, but even those include some duds, such as the high-concept retelling of The Metamorphosis that mostly leaves you scurrying between characters to read their dialogue. An adventure by the creators of the off-kilter TV show Robot Chicken mixes a funny story with terrible design: You pick from several doors to progress, but we spent a half-hour wandering around without knowing we’d lost. Worse, we regularly had problems moving in many adventures, getting stuck behind objects, walls, and ambient characters.

Galactic Adventures gives you more than 200,000 crowd-created moments and the tools to build your own. The winning potential of your own stories offsets much of the inconsistent execution.

Spore: Galactic Adventures
COMPANY: Electronic Arts
CONTACT: www.ea.com
PRICE: $29.95
REQUIREMENTS: Intel Core Duo processor; Mac OS 10.5.6 or later; ATI X1600, Nvidia 7300 GT, Intel GMA X3100, or better graphics card with 128MB VRAM; full version of Spore
Vast quantity of player-created adventures for download. Fairly open-ended tools script different experiences. Adventures moderately connect to the regular Spore space age, letting you earn spaceship power-ups. ESRB rating: Everyone 10+
Combat mechanics are often clunky. Hard to navigate and find adventures you'll like. Adventures are linear, so you can't build multiple-choice stories. Some adventure elements are always the same, such as the dancing-character ending when you win.