Great game that has its flaws and may not appeal to you
Spore starts off with you selecting a single planets. Planets act like houses in The Sims in that they are saves and there is only one save per planet. This is actually nice because it makes the galaxy feel more like one big model instead of a series of separate save games. There are five different games in Spore: Cell, Creature, Tribal, Civ, and Space. The idea is that in each world you can guide a single line of organisms from the beginning of time to far in the future. This works well enough, but some stages are better designed than others.
Cell stage is often cited as the best designed in its scope, despite being the shortest and simplest stage. Cell does feel more like a living breathing environment than later stages, and on the harder difficulties, you get the sense that the ecosystem around you is in constant competition. The gameplay itself is simple, you have an animal cell that either eats other animal cells, plant cells, or both. You move the cell around in a fluid 2d plane, trying to survive and not much else. Oddly, as simple as the game is, it's quite addictive and you can play though it several times without getting bored. The only gripe I have with it is that you go onto the next generation by mating. I can suspend my disbelief well enough, but as a game that is supposed to model reality (even in a cute and accessible way) this is only the first of many issues to come.
Creature stage was one of the most anticipated parts of the game, but it's also the weakest. In the first playthrough, you'll notice that everything looks really good. Creature is the only stage where you see everything from the ground level, and its very atmospheric. Unfortunately, the gameplay doesn't offer much and on subsequent playthroughs you'll either be rushing to get to space you'll end up grinding just to get all the parts and DNA points to make a creature that looks really good in later stages. This leads right up to another major flaw, many of the creatures in creature stage look unfinished because of the sharing system, more on that later. There are some neat events that happen in creature like UFO visits and meteor strikes, but you'll notice that they happen in pretty much every game, and the novelty wears out quickly.
Play is pretty simple. Carnivores eat other creatures, herbivores eat fruit. Carnivores gain DNA points and progress through the game by eating, but nicer creatures also progress by befriending other species. In whole, it all feels artificial. The sense that you are living in an environment with rules and structure that model our own is lost.
Tribal stage is probably one of the most disliked, but I actually enjoy it quite a bit. It's a very simple RTS game with mechanics that are very similar to creature, but it's also short, and the details are really nice. It's funny to just watch your creature dance around a fire or fishing. If it were longer, it would likely turn annoying, but as it is, you finish it in an hour and unless you're really slow you aren't likely to have time to get bored.
Civ stage is hit and miss. Some may like it, others not. It's a slightly more complex RTS than Tribal, with three city types to choose from: Military, Economic, and Religious. Military civs conquer others by destroying cities, Religious cities convert them, and Economic cities buy them out. It isn't hard, but the different civs do play differently and it's fun to try them all out. In all, the stage is short and it wont be long until you get into the meat of the game.
Space stage is the largest, most expansive by far. Here it becomes a simple space exploration and colonization game. I've always thought those genres were bloated with features, but I love the concept and to me Space had an almost perfect balance. There is a lot to do in space. You can trade and do missions for other empires, start wars, and terraform worlds. Some mechanics are a little simpler than I would like, and random disasters like pirate raids and eco disasters are extremely frequent and add nothing but annoyance to the game.
It is a little disappointing that it isn't until you get to space that the game really becomes non-linear. None the less, for those who would like, there is plenty of room to make your own stories in Space, the possibilities are endless.
The editors in Spore are extremely powerful. Just about everything you see in the game: cells, creatures, buildings, vehicles, and spaceships, all have their own editor. Unfortunately, the game automatically shares anything you make in game, which in creature stage is particularly annoying because you have a severely limited budget, and the quality suffers.
One of the most important parts of Spore, the online features, unfortunately feel unfinished across the board. The Sporepedia is bare of interesting features, but there have been promises of updates. As it is, there is little to do in the Sporepedia but look at your content. Many little additions, like the sharable picture books featured in The Sims, would have been a welcome addition.
In all, Spore is one of the most ambitious games, and despite all its flaws, one of the best, I think. Only time will tell if the rougher parts of the game are ironed out, but as it is, if you are uninterested in the artistic capabilities of the game, the game itself may not be enough to keep you interested for more than a few hours.