In the game's opening cutscene, Shadow finds himself on the outskirts of Westopolis, wondering about just who he is. It is from here that the hedgehog watches with mild disinterest as the Black Arms' crimson clouds swirl over the city, disgorging alien legions into the heart of the metropolis as the Black Arms begin their invasion of the planet. However, Doom's Eye swims over to meet the Ultimate Lifeform, and an apparition of Black Doom commands Shadow to gather the Chaos Emeralds "as promised" before flitting away while Shadow is barred from pursuing by several explosions around him, pocketing the ground with blast craters. While he's not interested in following orders, Shadow reasons that whether he likes it or not, if Black Doom has knowledge about his past, then he needs to collect the Emeralds and put the alien to the question.
Shortly after arriving in the city, Shadow runs into the one and only Sonic the Hedgehog, who wants Shadow to help him "show the black creatures that we mean business" by repulsing the invaders. Conversely, after Shadow grabs the first (green) Chaos Emerald, Doom's Eye approaches (commenting that he is "late"), and sets him with the task of destroying the GUN Soldiers and their Gun Beetles defending the city as the civilians evacuate. It is up to the player to decide who to help; or to take the neutral route and just go straight for the second Emerald.
Westopolis is still under heavy bombardment as the Black Arms troops war against GUN Soldiers, while the Black Comet showers the city with orbital lasers impacts, as Shadow fights his way through the streets. Half-destroyed roads, buildings, and burning car wreckages litter the stage, and some buildings can even be seen toppling over during the stage. The "Red Fruits", as they are called in-game, are found in small clusters at various points in the stage. There are some metal bridge-like structures that are knocked down by the lasers that can provide alternative routes through the level. There are even some damaged buses that can be flipped over to crush foes, as well as speed limit signs that can be knocked down and subsequently used for bashing heads. As for the state of the city, the soldiers will sometimes comment that "the entire city is on fire!" during the stage. In later cutscenes, a soldier informs the G.U.N. Commander that the city of the United Federation connected up by Lethal Highway, is one of six urban centers hit by the Black Arms right at the start of their invasion of Sonic's world, and has received the heaviest casualties, due to weakened defenses, and that "downtown Westopolis is almost completely destroyed."
The following weapons can be found in Westopolis:
- Key #1: Right before you jump to the second checkpoint using the dash panel, to your right is a hidden section. jump over the pit and over to the wall on the left. Run along the wall to reach the area on the other side with the key.
- Key #2: Right after the second checkpoint, use the pulley to reach the upper portion, where the key is located.
- Key #3: To get this key you are going to need to be quick. Before the third checkpoint you will see two GUN Beetles that lead to a ledge. From the high part of the road, bounce off the two GUN Beetles using the Homing Attack . Triangle Jump to the wall, and run along the side to reach the ledge with the key. If you are too slow. laser beams will obliterate GUN Beetles.
- Key #4: To the left of the third Checkpoint is a caged area. Use your spin dash to roll underneath, and break the dumpster in the back to find the key underneath.
- Key #5: Pass up the Goal Ring with the Chaos Emerald, and use the dash panel to launch yourself between the buildings. As you are failing, the key will be on the right side. If you fail to get it, use Checkpoint 6 to warp back to cheackpoint 5 and try again.
|Annihilate the GUN forces!||Defeat all 35 GUN enemies in Westopolis.||10 GUN enemies should have been defeated by the time you reach checkpoint #2, 20 by checkpoint #3, 26 by checkpoint #4, 33 before checkpoint #5, and all 35 before the final checkpoint.
|≥ 30,000 points|
|< 5000 points|
Leads to: Digital Circuit
|Find the Chaos Emerald!||To complete the Normal Mission, all that is required of the player is that to reach the Goal Ring with the Chaos Emerald in it. Missions like these did not require the player to finish of any of the Black Arms or GUN Soldiers, but sometimes defeating them will make it easier for the player to get through the Stage faster.|
|≥ 32,000 points|
|> 10,000 points|
Leads to: Glyphic Canyon
|Drive off the black creatures!||Defeat all 45 Black Arms in Westopolis.||23 Black Arms should have been defeated by the time you reach checkpoint #2, 29 by checkpoint #3, 33 by checkpoint #4, 42 before checkpoint #5, and all 45 before the final checkpoint.
|≥ 30,000 points|
|< 5000 points|
Leads to: Lethal Highway
Behind the Secret Door
In other media
Westopolis is mentioned in the Archie Comics' Sonic the Hedgehog comic book series and spin-offs. In this media, it is a Human/Overlander settlement in Eurish and a city-state of the United Federation.
- To complete the game 100%, the player will have to play this stage 326 times.
- In Expert Mode, Dr. Eggman wishes Shadow good luck via a hint marker.
- This is the first game in the series to feature Sky Diving done at the beginning of the stage and at the very end past the Goal Ring in normal mode and before it in Expert Mode.
- The Stage has 36 GUN Soldiers instead of just 35.
- If one were to play with Sonic with 2nd controller not only does he Homing Attack Black Arms, but can also hurt GUN Soldiers with it. He seems to function more like Shadow than other hero characters; he can activate switches, put out fires, open locked key doors, and he even has a scripted Sky Diving sequence which can be done at the end of the level.
- Strangely while running at full speed with Sonic and then pull the control stick down to brake to a halt he shares the same hovershoe SFX as Shadow when he brakes.
- The hint bubble where Sonic suggests to Shadow that they use the homing attack on GUN beetles to cross a gap was originally supposed to have Sonic use the word "piss" (ie, "Hate to piss off GUN..."), but it was changed to "tick" in the final version.
- If a laser fires during the Doom's Eye intro scene, the crates underneath said laser will remain intact.
- The stage's music was remixed for the Enemy Territory stage for the Sonic Forces DLC, Episode Shadow.
- Shadow the Hedgehog Prima official guide