WarriorJS (GitHub: olistic/warriorjs, License: MIT, npm: warriorjs) by Matías Olivera is a game that you play by writing ES6 code. Each level is solved by moving the player and interacting with units which include archers and wizards. The simplest level is best by moving the player left, so you just edit
Player.js to include the line
warrior.walk() in the right place.
The warrior actually has hit points, and there are two difficulty levels: beginner and intermediate. The levels are JSON files, so you could make your own fairly easily.
Matías will be adding new levels over time, so to check if there are new ones run
npm outdated -g warriorjs.