A haunted window on a budget · RCWeb Halloween

01 / Start small

Spend on the image, not the extras.

Borrow or reuse a projector first. Try one window after dark before buying anything for a bigger display.

The screen

Here, “shower screen” means a plain, frosted or milky translucent shower-curtain liner. Choose something that diffuses light but still lets an image show through. Clear glass or a clear liner offers little diffusion; a thick opaque curtain blocks too much light.

AtmosFX explicitly lists a shower curtain as a low-cost alternative for window rear projection. This is a useful starting point, not a guarantee that every liner works equally well. [1]

Our practical approach: test a small area before mounting the whole sheet. Avoid printed patterns and strong surface texture. Hang it flat with gentle tension using clips, a tension rod or removable fixings suitable for your frame. Follow its care instructions for creases; do not iron plastic unless its manufacturer permits it.

The projector

Use a video projector with an input your computer can supply, usually HDMI. A decorative rotating-pattern light or a USB-only video player cannot run this interactive browser app.

Check brightness units. Look for a stated ANSI lumen rating. Bare “lumens,” LED lumens and light-source lumens are not interchangeable with measured image output. [2]
Check native resolution. “Supports 1080p” can describe the input, not the pixels on the screen. As a practical buying preference, look for native 720p or better; 1080p helps fine detail and QR codes.
Check the fit. Throw distance and minimum focus distance matter more than smart-TV apps here. Read the exact model's manual before buying.

A used office projector is worth comparing with a cheap new mini projector. For used equipment, request a working image, lamp hours, input details and replacement-lamp cost. For either option, a return policy makes a real window test possible. This guide does not endorse an untested model or promise a fixed lumen threshold.

02 / Build the illusion

The projector stays indoors.
The audience sees the other side.

Side view, not to scale. A slight height offset can help keep the bright lens out of the audience's sightline. On a small screen, scroll the diagram sideways.

Choose the view from outside
Check the window from the pavement or your visitors' approach. Fit the liner on the room side of the glass, covering the intended image area. Window bars will divide the image, so test where faces and bodies land.
Measure before shopping
Measure your available lens-to-screen distance and intended image width. Distance = image width × throw ratio. For a 1.2 m-wide image, a 1.2:1 lens needs about 1.44 m; a 1.5:1 lens needs about 1.8 m. These are calculated examples, not a projector recommendation. Check the model's projection chart and focus limits. [3]
A 1.2 m-wide 16:9 image is only 0.675 m tall. A tall window may need a smaller framed image or a supported portrait installation. The app adapts to portrait browser dimensions, but that does not rotate the projector's optics. Only operate a projector on its side if its manual allows it.
Darken, align and focus
Test after dark with unnecessary room lights off. Focus on the curtain. Start with a small, bright image. If the lens appears as a dazzling spot from outside, move the projector slightly lower, higher or sideways; then use the minimum keystone correction needed. AtmosFX recommends checking the beam from the audience's viewpoint. [4]
Keep the setup comfortable to use
Use a stable support, leave the manufacturer's ventilation clearance and keep the liner away from hot exhausts. Keep equipment dry, cables out of walking routes and access to the window clear. Keep enough path lighting for visitors, and direct the projection away from roads and neighbouring windows.

03 / Put the haunt in your hand

Make the window react.

RCWeb Halloween renders live animations. Your phone can steer a ghost, wave a skeleton's hand or cue a sudden appearance. All scenes are silent.

Connect the display
Connect your computer to the projector and put its browser on that display. Open Halloween on the RCWeb server. For a server running on your own network, use its network address, for example http://192.168.1.20:8080/halloween/ (replace the example address). localhost on a phone means the phone itself.
Join from your phone
Scan the display's QR code to enter Halloween Controls in the same room. On a home installation, connect the phone to a network that can reach the server; guest Wi-Fi isolation can block it. Join before hiding the QR panel. Keep the controller tab open.
Correct the view from outside
Open Settings → Mirror projection if the image reads backwards to your audience. Use either the projector's rear mode or the app's mirror setting as needed: two horizontal flips cancel each other. The app mirrors the whole display, including the QR and text. Check them from outside; your phone controls stay normally oriented.
Clear the stage
After joining, choose QR code panel → Hide. Connected phones keep working and can show it again; larger QR sizes help joining at a distance. Move the display's mouse or touch its screen to reveal the full-screen button. Keep that browser visible and prevent the display computer from sleeping during the show. Try Lean graphics if animation struggles.

Choose the mood in Settings → Animation style

Six styles, nine cards in each
Style	What the audience sees	Try this
Simple	Bright illustrated characters on black.	Mr. Bones → Wave! for a friendly greeting.
Cartoon	Detailed 3D-style versions of the same characters.	Pumpkin Patch → Glow! or Bounce!
Shadow	Dark silhouettes on a deliberately white background.	At the Glass → Press closer.
Spooky Glow	Luminous ghosts and spirits on black.	Veiled Wraith → Manifest or Disperse.
Jump Scares	Brief, sudden appearances with black pauses.	Choose a scene → Scare now!
Window composition	Nine glowing adults behind a waist-height sill, with perspective approaches and soft focus.	Key Keeper → Appear right, then Lean closer. Top of image: 2 m; sill: about 1 m.

Host the encounter

Select a scene picture, then use its action buttons. Where available, hold or slide on the direction pad to steer; release to hand movement back. One phone steers at a time, but all joined phones can use actions and select scenes.

For an operator-led display, join on your own phone and hide the QR. For a shared display, leave the invitation visible and let visitors join. Hiding the QR is a presentation setting, not an access lock.

Jump Scares repeat automatically, even in manual mode. Time between scares offers 3, 5, 10, 15, 30 or 60 seconds between starts (default 5). A scene initially opens after about two seconds. The app has no motion-sensor trigger or manual-only scare mode; press Scare now! to add a cue when ready.

Let it perform

Tap Start demo to begin with the next scene. Demo runs a 20-second performance for each card in the selected style. It also starts after one minute without controller activity, including when no phone is connected.

To take over, select a scene, steer, use an action or tap Switch to manual. Manual mode still returns to demo after inactivity. If you want to stay with one scene, keep using the controller; there is no permanent scene-lock setting.

Back to apps returns that phone to the app list while the display keeps playing. Projection preferences are remembered when browser storage is available; a display refresh restarts the performance rather than resuming its exact pose.

04 / Check it from the pavement

When the illusion needs a little help.

The whole window looks grey: The app's black pixels cannot remove ambient light or a projector's residual light. Reduce room light and spill, try a smaller image and judge from outside. Shadow intentionally fills the background white. A shower curtain will not become completely invisible.
There is a bright spot in the middle: Check whether you can see the lens through the sheet. Adjust its height or angle and retest from several viewing positions. If the material stays patchy, compare a more evenly diffusing liner or purpose-made rear-projection fabric. [5]
The picture is dim or soft: Try a smaller image, refocus, reduce keystone correction and flatten folds. Test the liner's transmission before replacing the projector. More claimed lumens alone do not establish the result.
The QR will not scan, or the phone will not join: Check orientation from the audience side, enlarge the QR and refocus. If scanning succeeds but the link fails, check the server address, phone network and room. Join using the computer's direct display while arranging the projector, then check the projected code separately.
A scene changes when nobody touches it: That is the one-minute automatic demo handover. Select the desired scene to return to manual. Jump Scares also have their own automatic repeat interval.
The animation pauses or stutters: Keep the display browser in the foreground, check sleep settings and try Lean graphics. The app pauses simulation in a hidden tab. Confirm the phone still shows a connection before relying on a cue.

Research notes / 16 October 2026

Read the original advice.

This guide combines the primary sources below with the current Halloween app's documented controls. Placement examples and show sequences are practical suggestions, not measurements from a physical projector test. No projector or shower-curtain model was tested for this guide. AtmosFX supplies the projection advice; this page uses RCWeb's own animations.

AtmosFX — Festive Fireworks Year-RoundSupports using a shower curtain or other semi-transparent material as a budget window screen.
BenQ — ANSI, light-source and LED lumensExplains why brightness labels need care when comparing projectors.
BenQ — What is a good throw ratio?Explains distance divided by image width and the importance of room size.
AtmosFX — Digital Decorating 101: Window ProjectionsCovers translucent screens, ambient light, lens hot spots and projector placement.
AtmosFX — Window Projection MaterialA purpose-made alternative; its maker describes improved diffusion and reduced hot spots.

Open Halloween Full app guide

A haunted window.A very ordinaryshower curtain.

Spend on the image, not the extras.

The screen

The projector

The projector stays indoors.The audience sees the other side.

Choose the view from outside

Measure before shopping

Darken, align and focus

Keep the setup comfortable to use

Make the window react.

Connect the display

Join from your phone

Correct the view from outside