Asphalt Legends Unite

As of the time of writing this guide, there are 69 total seasons in Career Mode, and you only need to complete 40 of them. This will still be a very long term achievement (around 100 hours or so) because you will constantly need new and starred up cars to progress through seasons.

Initially seasons will unlock linearly as you complete one, but as you progress you'll start unlocking many mores seasons. This is good, because you'll end up getting stuck in seasons where you don't have any cars good enough to progress anymore, so you can expect to have 10-15 in progress seasons all at once. The "Show Off" and "Owned!" achievement solutions have more information on how to best unlock and star up cars, and that's really what you're going to need to do to complete more seasons. Additionally, don't necessarily be deterred by the recommended rank for each race. I was readily winning races where I was 100 points below the recommended rank, and would usually still try up to 150 or so below, but 100 points below was always a guarantee that I'd manage a win. So keep that in mind - it's worth trying to win a couple times even if you're below the recommended rank.

One other important thing to point out is that you unlock new seasons based on number of career flags, not just for completing seasons. So there were a bunch of times where I was stuck on many seasons and couldn't finish them, but what I ended up doing was playing some levels just to complete the extra challenges (other than the ones for winning) just to get more flags to unlock more seasons. You can check around and tap on the locked seasons to see what's required to unlock it, then do that so you have more seasons to work with.

Expect to be somewhere around 80 hours into the game, around 900-1000 career flags earned, and around 25 or so cars by the time you unlock this achievement, just to put it in perspective. Again, refer to the "Owned!" achievement solution since unlocking and starring up cars is the rate limiting step in this game.