Build the readable horror silhouette first
Players should understand doors, hazards, interactables and navigation before they appreciate micro-detail. Spend geometry and texture complexity where it changes silhouette or gameplay read.
Use a small prop family, not random clutter
A coherent set of dungeon, cemetery, ritual, bone, ruin or corrupted-environment props usually reads stronger than unrelated one-off decorations. Reuse material language and scale rules so the scene feels intentional.
Test darkness on the actual target display
Horror lighting can hide collision edges, doors and pickups. Check the demo on target hardware and make sure important geometry remains readable without flattening the mood.
Spend polish on the first 10 minutes
Event traffic is impatient. Make the opening interaction, first threat, first objective and first visual hook reliable before expanding the rest of the demo.
Fill one missing asset instead of rebuilding the set
If the scene is already coherent, buy or commission only the prop that is genuinely missing. A focused asset is usually cheaper and safer than replacing a whole environment near an event deadline.
Official event reference
Independent production checklist; not affiliated with Valve. Verify final event eligibility and dates in Steamworks.