Arduino Analog Input
NeoPixels
Tinkercad circuit: https://www.tinkercad.com/things/bz8QBfLM4Ol-rgbw-strand-test?sharecode=WRPSc8_1vuxC2CCHnyANICuJc5PxRZdkdhFljR9TNUI
Halloween Proposal
1. LED Face Changing Mask
My first idea is a LED face changing mask. The mask can have many expressions and images lit up on an LED board. The face will switch when I swing my hand in front of my face.
This mask requires the use of an LED board, programing of the difference mask designs, and a motion sensor.

2. LED Dress
The second idea is a LED Dress. Like how the dresses women wear in the European palace a few hundred years ago, this dress will have a LED skeleton. The color changes every step I walk.
This costume will need led strips, pressure sensor, and programming of how the light changes responding to my walking.

3. Two-faced Ghost
My third idea is a two-faced ghost floating and following me from behind (or resting on my shoulder). The ghost will have two facial expressions lit up with LED strips – an angry face and a loving face. The face will change to a loving face every time I flex my muscles.
This costume will need to use a muscle sensor, LED strips, and programming for changing faces.

Nice brainstorm, Sige! I like your two later ideas more than the first one, just because the first one is something you can already buy: https://www.amazon.com/Ompusos-Gesture-Transforming-Halloween-Masquerade/dp/B0BBVW17LP
To make a circuit change every time you step, I would recommend putting a vibration switch at your ankle, and running wires up to the circuit maybe in a fanny pack. Buy two of each style: fast, medium:
https://www.adafruit.com/product/1766
https://www.adafruit.com/product/2384
I’m not sure which of these is the right level of “triggerability”, also they’re cheap and easy to break. but its def not the slow one: https://www.adafruit.com/product/1767
For the third idea, this is totally doable with this easy-to-use product: https://www.adafruit.com/product/2699 HOWEVER your muscle is going to get super tired by the end of the evening on Halloween. I recommend also adding a regular pushbutton (and prototyping with one until your muscle sensor arrives) so you can still change the LED animation without the muscle sensor.