I love stuff like this. Around 2008 or so I was working on a Java game for the T-Mobile Sidekick (aka hiptop). The platform let you register url scheme handlers so I registered "drod" (the game was a from-scratch port of Deadly Rooms of Death, a classic shareware game). Since the game was a 16x16 grid-based game with 3 layers, it was super efficient at expressing levels, including monsters and locks and keys, with just a limited number of bits. On my website I had "DLC" in the form of drod://[base64 encoded level here]. It always filled me with joy that users already downloaded the levels when they navigated to the website. Clicking the link just opened the game with the data they already had on their device.