Comment by bogwog
I had an idea once but not the time nor motivation to build it: a database of game design with links to gameplay snippets.
So for example an article on "2D platforming" that discusses the implementation in Super Mario, and includes a "demo" button which launches a web emulator with a save state that demonstrates a specific jumping section of the game.
Legally perilous maybe, although my non-lawyer brain sees that as fair use, especially if the emulator doesn't let you play the full game. Idk, but it'd be a unique thing on the internet.
Edit: this is awesome btw, im definitely setting up a personal instance soon
Cool idea, would be a fun POC or weekend project. The team behind EmulatorJS (https://emulatorjs.org/) has made it stupid easy to inject the player into a static website (or multiple players with iframes), with a preloaded game and custom settings.