once they're hooked you can change the rules

Pondering game mechanics for RPGs I will never write.

So, you start off as PUNY FIRST LEVEL SCUM struggling your way through deadly dungeons. Only there are these wonderful magic potions you can use which temporarily boost your effective level. And they stack. Take a few of these and suddenly you're super-powered and can slaughter the opposition.

Of course, they have limited duration... and while you're boosted, you don't earn XP.

But that's okay! You don't need XP when you've got power potions! As long as you can kill stuff fast enough to earn enough gold to buy more potions, everything is fine!

... until you get later in the game and somebody achieves a stranglehold on the power potion supply. Now, if you want more, you're going to have to work for us... or else you're going to find yourself in big trouble up against the monsters in the current level of the game.

Sure, it'll get eyerolls as an obvious drug metaphor, but the point is that it ties in gameplay mechanics and story consequences without having to railroad or make a huge ooga-booga moral posture about it. And it doesn't have to be a drug metaphor - ANY sort of reliance comes with weaknesses. Your DRM could turn on you. Your publisher could drop you. Your job could fire you. Windows could release a new OS that doesn't allow games to run.

If you've planned ahead, carefully balanced your resources, and not relied too heavily on the power potions, you may have levelled up for real and still have a supply handy to take on the final boss.

If you've planned ahead, the company layoffs hopefully won't leave you at a complete loose end.

If you're relying on one thing only, then all anyone has to do to control you is to control that one thing.