When I first started playing Spore, I have to admit I was addicted to it quickly. The game is one big toy for the most part. It starts by you evolving from a single cell organism and goes onward from there to being a creature, to a tribe of creatures, to a civilization, and finally to going into space.
At each stage, you see new challenges added. At first, it's a giant game of Pac-Man. Avoid the nasties, each food, and grow. As you grow, you get to build onto your creature, adding weapons and other items. Then, you make land fall, and redesign your critter into a land dwelling animal. Now you have new challenges. You need to eat to live, and you need to either befriend or conquer all the other races on the planet.
With that done, you move to tribe mode. Now you no longer control just one of your creatures but a whole tribe. You manage your resources, and again befriend or conquer the other tribes to be dominant.
The civilization mode is very similar to tribe mode, but now on a global scale. To this point, you micromanage less, macro-manage more. In the Creature stage, you need to manually get food, in Tribe, you can order others to do it, and in Civ mode, there's no need at all to do it. Simply claim a resource and move on.
Then the wheels fall off the game once you reach space.
In every other mode, you do not need to struggle for resources. If you are smart, and plan well, you can focus on the goal of the stage. The same is not true in space mode. In Civ mode, you begin using money as your "points" to purchase new items (in other stages, it's DNA and food). Now, you can max out your cash, which is only 999,999 Spore bucks, a very small amount in space where some items cost upwards of 3 million spore bucks... but it doesn't carry into the Space stage.
Now, in order to make money, which is needed for everything you do in space mode, you need to manually run around to make it. You need to do missions, manually pick up and sell spice by locating the best price for it, or conquer other planets and collect the money dropped from space ships and destroyed cities.
The final, and absolutely most annoying thing in space: Ultra-micromanagement. Often the game will throw "random" events at you. "Random" is in quotes because it's not really random. The game basically penalizes you for moving forward in the game. Spend enough time away from one part of your empire, you will find them crying out for your help. Wage war on someone, and suddenly they will attack you in the middle of you attacking them. And instead of being able to let you planet fight back or arm them to defend themselves, you often need to return to fight off the invaders.
Now, if that wasn't annoying enough, you have to remember the goal of the game is to reach the center of the universe. So you have to leave your home galaxy. You must move inward. So that means as you try to get closer to the center, you must repeatedly return home to manually care for disasters going on in your home system.
And, if THAT wasn't a big enough pain, the entire center of the galaxy is controlled by a hostile alien race known as the Grox, and if you do ONE THING wrong, they will go to war against you, making it virtually impossible to reach the center of the galaxy, since you need to conquer their vast empire to bypass them.
And, if THAT RIGHT THERE isn't horrible enough... the closer you get to the center, the slower it gets. Throughout space mode, you buy upgrades for how far you can fly. except... all of that gets taken away, so now you will eventually be unable to reach the center through certain routes, which winds up making you run even more to try to complete the game.