Midnight Hospital

Making a first-person
horror game
with AI videos

Varick Lim, Creative Engineer

I build tools and make videos

GenTube Film Fest 2025 · Ghost in the Machine · Varick Lim

AI UGC · Varick Lim

Midnight Hospital

hospital.vamonke.com

Midnight Hospital
MiniMax

MiniMax H3

#1 open-weights video model on Artificial Analysis

33B parameters, free to download and build on

15-second clips with native stereo audio

Spoken dialogue in 11 languages

Text, images, video and audio in, one model

Midnight Hospital
MiniMax

MiniMax H3

→fal

H3 Max Turbo

Post-trained by fal for speed

Midnight Hospital
Slower than real time

Movies

10×
longer to make than to watch
20+ hours of footage for a 2-hour movie
Real time

Live streams

1×
as long to make as to watch
1 minute streamed, 1 minute watched
Faster than real time

AI videos

<1×
less time to make than to watch
15 seconds of video in under 15 seconds
Midnight Hospital
Before

Made in advance

Every scene is shot or rendered before anyone plays

→
Now

Generated while you play

Each scene is made the moment the player needs it

Midnight Hospital

Let's play

hospital.vamonke.com ↗

Midnight Hospital

How I made it

Building
OpenAI CodexGPT-6 Astra
Claude CodeClaude Opus 5
Look
Midjourneystyle references
Video
MiniMax H3 Max Turboevery scene
Stills
Nano Banana Litewhere each scene ends
FLUX.2 Kleinhand-picked key frames
Checking takes
Video understandingdoes the motion match?
Audio understandingis the dialogue right?
Choices
Moondream 3finds the doors in each frame
Hosting
CloudflareWorkers · Containers
R2 + D1video files · game data
Midnight Hospital

Midjourney as a style browser · --sref 82058305

Midnight Hospital

The original plan

Every scene generated live
QualityHard to control when a system generates every scene on the fly
Unlimited branches
CostEvery choice doubles the paths: 10 choices, 1,024 paths
Midnight Hospital

The original plan

Every scene generated live
QualityHard to control when a system generates every scene on the fly
Unlimited branches
CostEvery choice doubles the paths: 10 choices, 1,024 paths
Midnight Hospital

What shipped

15 rooms · 22 paths between them · 52 ways through

One personalized scene per player · 38¢ each

How the name scene is made

First frame
…a patient-name card reading exactly KAREN…
Prompt template + player name
Last frame
H3 Max Turbo15s · 480P
Their name scene
Midnight Hospital

Hiding the wait

Type your name
Read the instructions
Dark ward loop
The Surgeon
Your name
Generating name scene
Ready
Midnight Hospital

Midnight Hospital

The bill

AI models on fal
$171.90
7 hours of video generated
minimax/h3-max-turbo$158.08
google/nano-banana-lite$9.06
openrouter/router/vision$1.59
fal-ai/video-understanding$1.43
10 other endpoints$1.74
Coding agent
$200/month
~1.1 billion tokens
OpenAI Codex · GPT-6 AstraChatGPT plan
Midnight Hospital

Lessons learned

1
Decide the vision first

Vague instructions cause confusion and scope creep: more tokens, poorer results, more time cleaning up.

2
Start manual, then automate

Do it by hand until you know what good looks like. Then build the end-to-end system.

Midnight Hospital

How the models rank

Artificial Analysis — image-to-video leaderboard

Contra Labs — Ad videos: six models across ideation, mockup, and refinement

Go get caught

hospital.vamonke.com

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