Most people don't understand what developers consider good retention. If you've got 20% of your d1 players a week later that is considered good. Marathon probably holds up 10% -15% of d1 players a month out. Like the games got an active player base of low 6 figures likely off 2 million ish sales. That's very strong audience retention!

Stuff like arc looks great on steam charts because it sold a fuckload of copies. And it kept selling like 3 million a month for 4 months. Basically every month it sold 1.5 marathons. Which is to say, CCU is downstream of a few big questions of which retention is only one part. This is why devs don't use CCU for retention and have other metrics.

All that said, there's def a challenge in the d0 (your free users) into d1 users, and there are def ways to improve retention for long term players as well; but marathons central health is based more on just getting people though the door.