What is .ECL file?
Game file used by Touhou games such as Double Spoiler and Ten Desires; contains a stage script, which provides the locations of enemies and the form of "danmaku patterns," which are the patterns of enemy bullets shot on the screen (e.g., spirals, circles, etc.).
Touhou games are vertical scrolling action games developed by Team Shanghai Alice.
NOTE: ECL scripts can be decompiled using Touhou Toolkit, a command line utility.
Recommended Software Programs to open .ECL file