Add a leaderboard for solo, duo, trio, and quad runs across different categories - for example, fastest Primus kill, highest level reached, most monsters killed, and so on. For each Traveler.
Alternatively, you could introduce Weekly (and maybe even Daily) Challenge Runs with a set seed.
I’m not sure what percentage of the playerbase enjoys the competitive side of things, but I definitely do. Without it, the game starts to feel stale pretty quickly.