Macintosh.js
Whether nostalgic for a simpler era or just wondering what computing was like 20-some years ago, Macintosh.js lets you find out. Built by developer Felix Rieseberg using Electron and Javascript, it emulates a 1991 Macintosh Quadra 900 running Mac OS 8.1. Thanks to a 1997 MacWorld Demo CD, it includes a number of apps and games, including Photoshop 3, Illustrator 5.5, Civilization II, and, of course, Oregon Trail. A great way to waste an afternoon, it's available for free for macOS, Windows, and Linux.