TIS-JS is a TIS-100 emulator written using HTML, CSS and JavaScript. TIS-100 is a fictional computer featured in the game, also called TIS-100, made by Zachtronics. The objective is to write programs, using limited resources, to perform specified tasks (in which the old code has become corrupted).
Clone or download the repository and open index.html in your favorite
browser to run the emulator.
You can buy TIS-100 on Steam or GOG. I prefer GOG as it's DRM-free, but go with whichever you prefer.