The core of the Illvelo Swamp stage layout is a complex, 7-stage branching structure where your route is determined by your collection of 'Mare' items and specific in-game actions. Unlike a linear shooter, your path through the swamp is not fixed; it splits dramatically after Stage 2 and again after Stage 4, leading to entirely different levels, bosses, and one of four distinct endings. Mastering this system is the key to seeing everything the game has to offer and achieving the true ending.
This guide provides a complete visual flowchart and breakdown of every route, condition, and secret, turning a chaotic journey into a clear, plannable mission.
How Stage Branching Actually Works
Progression in Illvelo Swamp isn't about score. It’s dictated almost entirely by the Mare System. Understanding this mechanic is the single most important factor in controlling your path through the game's layout.
The Mare System: Blue vs. Red
Throughout each stage, defeated enemies release small pickups called Mare. They come in two primary colors:
- Blue Mare: These are the most common and are released by default from most enemies.
- Red Mare: These are rarer and are typically released by destroying larger, more dangerous enemies or specific parts of bosses.
The game constantly tracks two things: your Total Mare Count for the current stage and your Blue Mare Ratio (the percentage of your total Mare that is blue). These two values are checked at the end of specific stages to determine which level you proceed to next. Generally, a high Total Mare count and a high Blue Mare Ratio lead to the harder, upper paths, while lower counts or a focus on Red Mare lead to the lower, easier paths.
Illvelo Swamp in-game screenshot
The Two Critical Branching Points
While your performance is always being tracked, the stage layout only splits at two specific moments. Getting the route you want means preparing for these gates.
- After Stage 2 (Foggy Marsh): This is the first and most significant split. Your performance in Stages 1 and 2 determines which version of Stage 3 you'll enter. This decision sets you on a broad path (Easy, Normal, or Hard) for the middle portion of the game.
- After Stage 4 (Varies by Route): The second major branch occurs after you complete your Stage 4 variant. This choice is even more critical, as it locks you into a specific set of final stages (5, 6, and 7) and determines which endings are available to you.
There are also minor variations and secret rooms within stages, but these two points are the moments the entire world map reconfigures based on your play.
A Stage-by-Stage Route Breakdown
Here’s how the paths unfold, stage by stage. We'll refer to the routes by their common fan designations (A-Route for the top/hardest, B-Route for middle, C-Route for bottom/easiest).
Stage 1: Ancient City of Illvelo & Stage 2: Foggy Marsh
Everyone starts in the same place. These first two stages are your qualification run for the first branch. Your goal here is to collect as much Mare as possible and manage your Blue/Red ratio according to your desired path. To aim for the hardest route (A-Route), you need to aggressively collect Blue Mare and destroy every enemy possible to maximize your total count.
The First Split: Entering Stage 3
At the end of Stage 2, the game checks your stats and sends you to one of three possible Stage 3 versions:
- Stage 3-A (Ruins of Memory): The hardest path. Requires a very high Total Mare count and a high Blue Mare Ratio (typically above 85%). This route is characterized by dense enemy patterns and a challenging mid-boss.
- Stage 3-B (Submerged Passage): The normal path. Achieved with a moderate Mare count. This is the most common route for a first playthrough.
- Stage 3-C (Fungal Grotto): The easiest path. Results from a low Total Mare count or a low Blue Mare Ratio. Enemies are sparser, and the overall difficulty is lower.
Your path is now set through Stage 4. If you entered 3-A, you will proceed to 4-A. If you entered 3-B, you go to 4-B, and so on.
The Point of No Return: Clearing Stage 4
The boss of your Stage 4 variant (e.g., Zassoudou on the A-Route) is the final gatekeeper. Your performance across Stages 3 and 4 determines your final path. This is the most complex branch, locking you into your ending route. The conditions become stricter, with some paths requiring near-perfect play.
Illvelo Swamp in-game screenshot
For example, to stay on the hardest path (the A1-Route that leads to the True Last Boss), you must not only have a high Mare count coming out of Stage 4-A but also meet other potential hidden conditions, such as a high kill count or avoiding deaths (no-miss).
The Final Gauntlet: Stages 5, 6, and 7
From here, your path is locked. You will play through the Stage 5 and 6 variants corresponding to your route, culminating in a final confrontation at Stage 7 against one of several final bosses.
- A1 Route (True Ending Path): Stages 5-A1, 6-A1, 7-A1. This route is brutally difficult and leads to the True Last Boss.
- A2 Route (Good Ending Path): Stages 5-A2, 6-A2, 7-A2. A slightly more forgiving version of the hard path.
- B Route (Normal Ending Path): Stages 5-B, 6-B, 7-B. The standard conclusion to a solid run.
- C Route (Bad Ending Path): Stages 5-C, 6-C, 7-C. The result of a low-performance run, leading to an unsatisfying conclusion and a much weaker final boss.
How to Unlock All 4 Endings
Achieving all four endings requires multiple playthroughs, each targeting a specific route through the Illvelo Swamp stage layout. The conditions below are general targets; the exact Mare thresholds can be tight.
| Ending | Route Path Required | Key Conditions | Final Boss |
|---|---|---|---|
| Bad | C-Route (e.g., 1 → 2 → 3-C → 4-C → 5-C...) | Low Total Mare count throughout. Fail to meet the gates for B or A routes. | Larva Form |
| Normal | B-Route (e.g., 1 → 2 → 3-B → 4-B → 5-B...) | Maintain a solid, but not perfect, Mare count. The standard outcome. | Imago Form |
| Good | A2-Route (e.g., 1 → 2 → 3-A → 4-A → 5-A2...) | Achieve and maintain a high Total Mare and Blue Mare Ratio, but miss a secret condition. | Imago Form (Harder) |
| True | A1-Route (e.g., 1 → 2 → 3-A → 4-A → 5-A1...) | Very high Mare counts, high Blue Ratio, AND fulfill a secret condition (often a no-miss run on certain stages). | Mother (TLB) |
Illvelo Swamp in-game screenshot
Frequently Asked Questions
How many stages are in Illvelo Swamp? A single playthrough consists of 7 stages. However, due to the branching paths, there are over 15 unique, individual stages in the entire game. Seeing them all requires multiple clears on different routes.
What is the 'true' final boss? The true final boss, often called "Mother," is only accessible on the A1-Route. This requires taking the most difficult path at every branch and fulfilling a secret, stringent condition, which is widely believed to be a no-miss (no-death) performance in the later stages of the game.
Can I see all stages in one playthrough? No, it is impossible. The stage layout is designed with mutually exclusive branches. At the end of Stage 2, you are locked into one of three Stage 3s, making it impossible to visit the other two in that same run.
What's the easiest route for a 1-Credit Clear (1CC)? The C-Route (the lowest path) is by far the easiest for securing a 1CC. By intentionally keeping your Mare count low or collecting more Red Mare, you can force the game to send you to Stage 3-C and the subsequent easier levels. The enemy patterns are less dense and the bosses have less health.
The Swamp is Meant to be Explored
The genius of Illvelo Swamp's design lies in its replayability. The branching stage layout isn't just a gimmick; it's a core mechanic that rewards mastery and exploration. Each route feels like a distinct experience, telling a slightly different version of the game's abstract story. Don't be discouraged if you get the "bad" ending on your first try. Instead, see it as the swamp inviting you back to uncover its deeper, more dangerous secrets.