Assymetrical space 4x.
Humans took to space - we developed our first ships, made our first interplanetary conflicts, settled on some of the Solar System bodies but its still mainly domed cities/orbital habitats stuff, no neat terraforming, no FTL, no clinical immortality, all-diesease cures etc.
One day, USS Pegasus ( Fletcher class destroyer - newest and most advanced ship in the Terran Navy), patrolling the outskirts of Human controlled Solar System, detects large ship appearing out of nowhere and second waay smaller that is chasing him. Brief battle ensues that leaves the Pegasus crippled with many wounded and dead but luckily they managed to destroy the attacker. The big ship explains the situation - they are civilian freighter from race X* that were attacked by the pirates and having their hyperdrive destroyed they had to risk jumping trough uncharted wormhole hoping the pirates wont follow them..
Yes, that ship that almost destroyed our newest destroyer ?? That was just some dinky little pirate ship..
The other side of our galaxy is full of ancient powerfull races, with thousands of planets, quadrillions of citizens and tech that looks like magic when compared to our own. Some of those races are hostile, some of them are peacefull, isolationist, benevolent etc.
Player is completely outclassed, outgunned and out-teched at the beginning - you have to move very carefully, use espionage, diplomacy, make allies, help minor races, battle pirates, colonize planets taking advantage of the our relative isolation etc.
Other races are very stale and conservative when compared to us but they also advance - wars broke out, new discoveries are made, Galactic Senate mends the deals between member countries, lets new one join, kicks other for attacking each other, there are factions trying to pass various resolutions etc.
In time human role will improve, rivalling many of the already established nations ... just when galaxy frontier starts being attacked by a unknown intergalactic threat that makes all those races look like caveman.
* - different each time and that means different starting relations with different nations, starting techs, bonuses etc.
And of course whole game with Aurora level of detail and Star Ruler scale, with REAL emphasis on diplomacy and espionage - especially at the begining when single corvette could erase entire human race out of existence.
I would love to see Arcen Games take a shot at it - they made some of the most original and fresh space 4x/strategy titles in the recent memory.
Reason why we are isolated like this ? Great Intergalactic Threat ( the one that is coming back ) chased benevolent Precursors all over universe. Precursors, in a desperate gambit, launched thousands of seeding probes into most distant galaxy they could detect - Milky Way and made their last stand. Probes where programmed to seed life on various planets that were relatively close to each other to force those races to interact and develop quicker. "Our" probes hyperdrive malfunctioned sending her faaaar from others and she acted on the emergency protocol and seeded Earth..