What projects have you worked on? (500 char limit)

The project that still stands with me after years after I started it is a scavenger hunt platform (https://github.com/wlmac/scavenger).
The main difference between this and just papers links scattered around a building or a website is that this has an anti-cheat.
By hashing the id + the team and hunt’s ids, we can generate a unique path that each team has to follow. If team A tries to follow team B, they won’t be able to scan the qr codes as they are on different paths.