Obligate - a virus without a body

You are a virus. You have no body of your own, so you steal one. Touch a cell and it is yours: its shape, its weapon, its ability. Ride it until it fails, burst out in a swarm, and take the next one before your time runs out. A twin-stick roguelite where every enemy is a body you could be wearing.

Every run starts on the body map. Three ways in: a skin wound, the airway, the gut lining, each a road to its own lymph node. The organs beyond them are drawn in and waiting for the full game.

Each run is one organ, grown fresh from a seed: five to eight chambers strung on capillaries, with the lymph node at the far end. Nests of host cells, immune patrols, ambushes. No two are laid out the same way.

Outside a host you are a capsid: fast, unarmed, and dying. The bar on your card is viability. When it empties you are gone. Everything you do in this game, you do to keep from being a capsid for long.

Find a host before your viability runs out.

There are no character picks. The cell you are wearing is your class, and you change class by changing bodies.

• Epithelial cell. Free to take, everywhere, and the floor of everything. A starter body.
• Red blood cell. Fast and unarmed. A way to cross a chamber, not a way to win one.
• Neutrophil. A shotgun with a sprint. Ugly up close.
• T cell. A sniper. Long range, quick, thin.
• Macrophage. The tank. Engulfs enemies whole and heals off what it hits.
• Dendritic cell. The boss. Cannot be killed, only taken.

Host cells are free. Immune cells have to be worn down first: shoot one below half, it starts to glow, and then you burst out of whatever you are wearing and touch it as a capsid. Now the thing that was hunting you is the thing you are.

This is the move the whole game is built on. Shoot an immune cell until it glows, press E to leave the body you are in, and touch it. For a second you are nothing at all. Then you are the thing that was hunting you, with its gun in your hands.

And the organ will not let you skip it. Somewhere on the way to the lymph node the way on is shut, and it opens for one kind of cell: a clot only a macrophage can eat through, a plug of mucus a neutrophil dissolves, a checkpoint that waves a T cell past, a capillary too tight for anything but a red blood cell. Find one. Become it. Come back.

Ambush chambers swell shut behind you until everything in them is dead, or yours. And whatever you run past follows you to the lymph node. If you are stuck, the game says what to look for, then how, then points at it.

Bodies are temporary. Your genome is not. DNA fills the bar along the top edge; each level offers three mutations, and every gene you take rides with you from host to host, even when the body does not.

Eighteen genes, each stackable to its own cap. Some sharpen the cell you are in: split payloads, venom that stains what it hits, tropism that steers your shots. More of them pay you for not staying in it: a fresh host hits harder for ten seconds, every new kind of cell you ride makes all of them stronger, immune cells become yours sooner, and a burst leaves a turret behind. And the first time you ride a new kind of cell it teaches you a gene of its own, so exploring bodies is how the build grows.

Three strains to start a run as: the balanced wild type, a helical strain that survives far longer outside a host but tears easily, and an armoured one that is slow to move and hard to pop. A fourth is bought in the strain tree.

At the end of the organ waits the dendritic cell, the immune system's teacher. Killing it seals the node, so the game will not let you. Wear it down to the mark, leave your host, and ram it naked. If you make it, the immune system answers to you.

This demo is one full organ, from the title screen to the lymph node:

• Three ways into the body, each leading to its own lymph node.
• A host gate in every organ that only one kind of cell opens, and ambush chambers that seal until they are cleared.
• A procedurally grown organ of five to eight chambers, different every run.
• Six kinds of cell to ride, each with its own weapon, ability and shape.
• Eighteen genes, three strains, three host-immunity difficulties, and a seed you can share.
• The dendritic cell at the end, and the autopsy that follows every run.
• The strain tree and the codex between runs, so a lost run still buys something.

The first run teaches as it goes and then gets out of the way. Everything you have met is written into the codex, and a run takes about ten minutes.

W A S D	Move
Mouse	Aim
Left mouse	Fire
Space	Dash
Q	Host ability
E	Burst out of your host
Tab	Genome and host details
Esc	Pause

Full controller support, with every action rebindable in Settings. The game assumes a pad until the mouse moves.

Windows 10 or 11, 64-bit. Runs on integrated graphics; no dedicated card needed. The download is about 50 MB and the game takes about 120 MB once it is extracted.

1. Download. Press the download button on this page and save Obligate-0.5-demo-win64.zip. It is free; itch may offer a tip box first, and "No thanks, just take me to the downloads" skips it.
2. Extract. Right-click the zip, choose Extract All, and put it wherever you keep games: the desktop or Documents is fine. Do not play from inside the zip; Windows opens it like a folder, but the game cannot run from there.
3. Run. Open the Obligate folder and double-click Obligate.exe. There is no installer and nothing is added to Windows.

"Windows protected your PC"? That blue box appears for any game from a small studio that has not bought a code-signing certificate. Choose More info, then Run anyway. It asks once.

With the itch app there is nothing to do by hand: press Install, then Launch, and the app keeps the demo up to date.

Updating. Delete the old Obligate folder and extract the new zip. Your banked DNA, strain tree, codex and settings are kept: they are saved outside the game folder, in %APPDATA%\Godot\app_userdata\Obligate.

Removing it. Delete the Obligate folder. To wipe your progress as well, use Erase profile on the profile screen first, or delete the save folder named above.

Something wrong? README.txt in the folder has the controls, and Report a bug in the pause menu opens the feedback page with your run attached.

Obligate is made by one developer at Wickhouse Games Studio in Godot 4. It is a single-player roguelite with no live service, no microtransactions and no online requirement. This demo is an early build: tell me what worked and what did not in the comments. Every note is read.

How it was made. Every cell, membrane, organ and effect is drawn by the game's own code; there are no generated images in it. The sound effects and music were generated with ElevenLabs, then chosen, cut and mixed by the developer. The code was written by the developer with an AI coding assistant. Design, writing and balance are the developer's. Nothing is generated while you play.

With thanks to the Godot Engine contributors, and to the makers of the Syne and Atkinson Hyperlegible typefaces (SIL Open Font License). Full credits are in the game.