Sounds like a good idea for a new game.

Despite how much more advanced that it is in spacial technology doesn't nessisairly mean they will be much more advanced militarily or even medically.

Technological advances are VERY resource specific. Our perception of natural technological progression is biased on our own expierence.

A good example is gunpowder.  If a planet has no Potasium Nitrate... gunpowder may never show up.  (This can be seen to a lesser degree in how different technologies evolved at different paces in human history, which sometimes gets overlooked just based on the technological juggernaut europe is seen as by most.)

Or the dominate alien species might originate from a planet where most plants are toxic to them, so it's harder to discover medicines.

There planet might be covered in matierals PERFECT for space travel, and their lifespans and perception of time might be such that the time it takes to reach us is trivial.

Basically their might be alien race equivelent of ancient polynesians out there.

I'd guess they'd have pretty decent weapons if their plan was to invade though.   Generally though space aliens could really just orbitally bombard us with giant rocks until we surrendered if they really wanted to.

Like in Starship Troopers.

This scenario was best explored in Footfall, including how we could fight back and overcome (with devastating losses)
It would make a much better movie then Starship troopers or Independence day.

A Time Odyssey (Time's Eye / Sunstorm / Firstborn) is a more realistic scenario for Aliens that simply want to get rid of us. Burn the planet clean by throwing a well aimed rock into the sun to create a giant solar flare to sterilize the planet 800 years later.

In the Time Odyssey series, not-so-benevolent godlike aliens start an endless mission to regulate the development of sentient life in the Universe, in order to prevent all other species from harnessing too much of its energy, which would only accelerate the inevitable entropic death of the Universe, thus rendering sentient life impossible at the end of the universe. Consequently, these "Firstborn" are destroying other intelligent species.

This series is at the top of my list for a movie trilogy. It has the potential to be more epic then lotr. Apart from the real earth trying to survive an extinction event, there is a second story of random segments of history being duplicated on an alternative museum type patch work earth. In which for example Alexander the Great meets the armies of Attilla the Hun on the battlefield in ancient Babylon where a group of stranded astronauts are trying to survive.

(There are also stories of friendly aliens trying to help us, but you need to go back to the 50's for that. For example Childhood's end)