Learning to mix from scattered tutorials has an ordering problem: you end up knowing how to drive a multiband compressor before you're clear on how loud the vocal should sit against the guitar. Tools get learned in the order they show up in the feed, not the order they're needed — which is why plenty of people with years of videos behind them still can't resolve a simple mix.
Mission Mode imposes that order. There are 6 worlds, one per discipline, with 20 scenarios each and 120 in total. You go through them in sequence: balance first, the foundation for everything else, and mastering last, the thing least worth touching if what came before is wrong.
The order isn't rising difficulty for its own sake: it's the order decisions get made in a real mix. Nobody EQs a track well whose level they haven't settled yet, and compressing to fix a frequency problem is the fast route to a dull mix.
3 of 6: Balance, EQ, Dynamics. That's 60 scenarios without paying anything, covering exactly the three disciplines you need most at the start.
Because the order is the content. A mastering scenario assumes you can judge balance and dynamics; opening it early doesn't speed anything up, it just produces random answers.
Not required, but it helps from the second world on. The scenarios train the decision; trying it in your own session is what turns it into habit.
The first two worlds are for beginners. From Dynamics the bar rises, and Saturation, Space and Mastering assume you already make mixing calls with your own judgement.
Each discipline has its guide if you want the reasoning before or after playing it: EQ, compression, reverb and delay and mastering.