tbh, any system can accommodate this. It's on you as a DM to create/use the various larger factions/entities. You can really make a world feel alive by writing up a few basic opposing factions and having the results of their conflict intertwine with whatever your group is doing. Wanna run a Shadowrun game? Focus on the megacorps going at each other, have the party work some of those jobs, but maybe have another group of NPC runners crash a job. Wanna do D&D? Well, they added factions like the Harpers so that you can have some big players pushing pieces behind the scenes, and have your players stumble onto a wider conspiracy.

I think the biggest thing is that you can't be afraid to give your party a challenge you know they have no hope of defeating. If they're small fish in a big pond, they have to encounter a big fish and learn their place in the hierarchy. If your group is smart, you can give a lot of hints that they need to flee and escape the bigger fish. If they're dumb, have em get wiped out in combat and barely survive.

The world of darkness games can run like this. If you play new vampires, there's going to be a whole political landscape that is at best neutral to you. Same with Mage. The other types probably also, but I don't know them as well.

It does have a paradoxical element in that your character will be a big fish as far as the mundane world is considered. A freshly statted vampire or mage is far more powerful than a mundane person.

It does have paths for players to become big fish, too

Check out Blades in the Dark and Spire the City must fall.

I'm blades you pay an upcoming gang of criminals in a haunted Victorian steampunk city where every inch is owned/claimed by another gang so everything you do either pleases or upsets somebody. Definitely has the struggle to survive in a hostile world feel. Blades is one of my favourite game systems to run. It's soo easy for the GM I basically never needed to prep.

In Spire you play a group of rebel or terrorist dark elves fighting against the oppressive high elf regimen. The world building is really detailed maybe a bit too much in some places. I really enjoyed running it though.

I know of one, that being GUN by Abbadon, which might be a good idea.

Paranoia, is explicitly written that way. You don't win or change the world. You just survive it... a little bit longer... or not.

Call of Cthulhu is sort of another example, but the characters do tend to be outstanding in some way, just not in power-fantasy ways.

old d&d editions or OSR-Systems can offer that feel as player characters tend to be weaker than their 5e counterparts.

the world of darkness games might also be an option, but i've only watched/listened to some actual plays and there the player characters seemed like pretty small fish until they established themself as a politcal force through luck and schemes.

Kenshi, the game world doesn't just hate you, it doesn't even care that you're there.

Mount and Blade warband is the dated but classic sandbox. You don't matter unless you make it.

Kingdom come deliverance is more recent, but it's definitely got a learning curve and some players can't get the groove right.

Subnautica is a more literal interpretation.

Which would I recommend? Honestly all of them.

Chronicles of Darkness if you like the horror vibe.

• Rimworld
• Minecraft with Infinite Dimensions
• InZoi (maybe wait a few updates for it to get more polish)

Abzu