Systematic Immunity

A game by Felix Wunderlich for PC, originally released in 2016.
In Systematic Immunity, you take control of a cluster of white blood cells as they traverse a human body, moving from organ to organ to take down a nasty germ that is propagating a huge infection across its host. You must lead your army of cells through the stomach, lungs, and brain – each offering a unique set of precision platforming challenges – as you try to keep your cells alive long enough to reach the pestilence and snuff it out.

Players are equipped with the standard walk, run, and jump controls seen in other precision platformers, as well as the ability to wall jump up certain surfaces. The white blood cells have a floaty jump and a great deal of midair direction control, offering tools to the player who must maneuver them through tight spike-lined corridors, past rows of spiked enemies, and across huge chasms.

What makes this game different from other genre entries is the fact that you are controlling a set of 20 characters simultaneously. When each level begins, the cells are clustered close together, but they begin to spread out as the player moves around the environment, and they can get quite far apart when making jumps from curved surfaces, as each cell moves away at its own trajectory.

There is a button assigned to drawing the cluster back to the main cell – which is a brighter shade of white than the others – but this drains a meter at the top of the screen, and once the meter is depleted, this function is no longer available. However, each level offers one opportunity to refill the meter in the form of a floating information icon.

Many precision platformers offer secondary optional pickups, including bandages in Super Meat Boy, cookies in Fenix Rage, warps in Blitz Breaker, hearts in INK, and gems in iZBOT. In some cases, collecting these items leads to bonus levels, while others offer them simply for bragging rights. In Systematic Immunity, information icons refill the player’s meter for attracting cells and also unlock a biological tip which is displayed on the ranking screen at the end of the level. Players are ranked based on whether this icon was collected, the number of cells that survived to the end of the level, and completion time.

Rankings based on collection and completion time are staples of the precision platforming genre, as the player is tasked with mastering the specific controls of the character to navigate environments where there is little room for error. In Systematic Immunity, on the other hand, the player is not in complete control of his character, which significantly impacts the player’s ability to ply his skills toward fast completion times, high rankings, or even basic survivability.

Since cells spread out without input from the player, and since the player’s resource for pulling them together is limited, there are often times where one or two straggling cells will be shaved off by contact with spikes or enemies, or by simply missing a jump that the other 18 cells completed. Most levels require that the player successfully guide 15 cells to the invading germ cluster, if the cell count drops below this number, the level is failed automatically.

Further confounding the player’s ability to reign in his little white buddies are numerous collision issues and physics-based bugs: sometimes one or more cells will fall through a solid platform when hitting it at a high speed or otherwise split off from the group for no discernible reason; engaging and reengaging bubbles (more on these in a bit) sometimes causes one or more cells to get separated from the group and fall to their deaths; occasionally cells will quickly separate from one another or begin colliding with objects that don’t exist, such as having a few cells walking up an invisible wall while the others walk straight ahead; and there are numerous issues when hitting trampoline blocks from the sides, often resulting in cells being shot up off the top of the screen or hurled violently into walls of spikes.

With the challenge of basic navigation, combined with numerous issues beyond the player’s control, simply surviving the levels is challenge enough, without the player focusing on grabbing optional pickups, achieving high rankings, or unlocking the game’s many bonus levels. Fortunately, there is some buffer in the level select screen, as each world begins with three levels unlocked, and a new level is unlocked each time another is competed, so if the player gets truly stuck, he may come back to the level later, or skip up to two levels entirely.

At the start of each level, the cell cluster emerges from a red pustule, and the player must maneuver the group across the level to the infection at the end. Dangers include spiked enemies, projectile-firing enemies, stomach acid, electricity, and good old fashioned bottomless pits. Each area takes place in a different part of the body, each with its own themes and challenges. Areas are divided into chunks of 25 levels, with a boss fight at the end of each.

The first area is the stomach, which offers cilia walls to climb up and deadly stomach acid along the bottom. In these levels, the player’s ACTION button causes all of the cells to squat down into little balls that roll down sloped surfaces, and this is used to pass beneath rows of spikes and enter narrow passages. These levels also have some time-based challenges where the player must move quickly – and keep his cells close together – to outrun rising stomach acid.

World 2 takes place in the lungs, introducing several new gameplay elements, the most important of which is the ability to generate a balloon around your white blood cells. By jumping into the air and holding the ACTION button, a balloon appears and encapsulates your white blood cells (unless the cells are too far away from the main cell), allowing them to float gently around the area while descending very slowly.

Maneuvering in the balloon requires very precise control, as touching any enemy, projectile, or deadly obstacle will pop the balloon and kill all of the cells within, even if they themselves avoided contact. Later challenges play on this as players must engage the balloon to float across a gap and then disengage to hit a trampoline and launch the cells through passages that are too narrow for the balloon to traverse.

Players must use the balloon to descend through narrow spike-lined passages without touching the sides and to bypass clouds of smoke that emerge from the lung tissue, as the human host seems to be a 12-pack-a-day smoker. Not only are his lungs producing smoke, but many of the surfaces within his lungs are covered in a sticky black tar. Fortunately, this means that the white blood cells are able to stick to the sides and use the walls as platforms, walking freely around corners and under overhangs.

Controls are cell-relative, however, so players will need to be mindful that when walking upside-down, pressing RIGHT actually sends the cells to the left side of the screen. Additionally, players need to be particularly mindful when jumping from any curved surface, especially from the undersides of platforms, as cells are likely to be spread further apart in midair unless the player draws them together.

Additional challenges in the lungs include sequences where the player must move through updrafts, either following the currents or purposely disengaging the balloon in order to drop down. In certain levels, the human host breathes heavily (perhaps to expel smoke from his ruined air sacs), pulling the white blood cells upward quickly, often toward walls of spikes. Here, the player must deactivate the balloon lest he be sucked up even more quickly. Many levels also feature an insufficient number of cells at the start, requiring players to move through dangerous environments to collect cells from a secondary pustule before heading off to destroy the infection.

The final area is in the brain where the player must avoid beams of electricity and dastardly blobs that fire homing projectiles which are capable of following the cells around corners. The new gameplay element added here is a warp field that the player can jump through and activate from within. Doing so causes time to slow down, and the player is able to move a ghostly version of his cells to any point on the screen.

The player is restricted from teleporting inside of solid objects or teleporting to the other side of electrical currents, and electricity flashes on and off very quickly. Players must use the time dilation effect to watch for breaks in the electrical currents and make properly-timed teleports, and sometimes the player is required to make multiple teleports in succession. The player’s momentum is preserved when teleporting, opening up puzzles where the player must emerge from a warp, bounce off a trampoline, and warp again in order to pass over a high obstacle on the other end.

At the end of each set of 25 levels is a boss encounter against a beefed-up green germ. Each boss sequence offers unique gameplay not featured in the levels themselves, such as luring a boss to damage itself or performing a short shmup sequence by launching cells at a large creature that moves back and forth along the top of the screen. Players wishing to further explore some in-body platforming shenanigans may create and share levels of their own design by using the level creation tool.

Systematic Immunity was developed by Felix Wunderlich over the course of three years. This was his second commercial release following Plazma Being.