The TARDIS lands in the future and the future isn't looking too bright.
Dystopian science fiction set on Earth or a human colony world, generally with humans front and centre rather than alien invaders or the like, allow for a mix of prediction, satire, social commentary and killer robots.
2: I've seen the future... and it's pants.
They tend to feature bases which aren't currently Under Siege, alien vistas which may resemble quarries, and a cast of people who are the main causes as well as targets of problems.
They may occasionally be based on alien planets with humanity represented by the TARDIS crew, but if so, the non-human residents will be very much "people" with a variety of relatable traits and foibles.
Monster appearances can be provided by a small number of aliens, by robots or cyborgs, or by faceless Stormtrooper types with blasters, but this is more likely to be an obstacle, or the killer in a murder mystery, than a full-on besieging army. Consider how important the Macra weren't in Gridlock, or the cameo appearances of the Kandyman in The Happiness Patrol, the best Paranoia RPG crossover ever televised. A monster might be behind things, like the Mighty Jagrafess in The Long Game, but will still have human(oid) minions to blend in with the larger cast.
All dystopian futures in Who have some pressing "society has gone wrong" issue for the Doctor, companions and any plucky rebels in the guest cast to deal with. This can be something extrapolated from reality that genuinely bothers you, but this could make for un-fun issues-heavy games or rather blunt satire - I've done this, and it's less amusing than it sounds - or something wildly exaggerated to make it fun to deal with, either humorously or horrifically. The Cybermen started as one of these, to an extent...
The problem can be solved by talking with people, making peace between warring factions, possibly overthrowing a corrupt government, optionally making a robot explode and ideally blowing up a really big building.
The Doctor takes Emily and Richard to an artificial planet in the year 88,002. They're unpleasantly surprised to find faceless stormtrooper types forcing people out of their homes... and discover that the capital city is effectively shut down in preparation for being sold to cover the system government's debts. It's a massively excessive solution to a genuine problem, and evicting millions of people to make way for the various alien powers looking to buy the planet and strip its resources isn't going to go well. Riots break out in the streets as the ruling classes look forward to their planet-sized reward, but one of the potential buyers plans to break the planet into saleable chunks before the sale goes through...