I've played through all 3 Mass Effect games and now I'm watching Firefly. I noticed that Jayne (the mercenary) wears a "Blue Sun" muscle shirt and in Mass Effect, the Blue Suns are a mercenary company. This got me to thinking...
Both take place in the future in space and follow a single ship and it's crew.
The lead in both is captain of the ship, good with a gun and has a keen moral compass (in Mass Effect the player can influence morality).
There's a Shepard in Firefly and the main character in Mass Effect is Shepard.
There is a race of undead "aliens" in Firefly called "Reevers". In Mass Effect the "Reapers", an alien race, raise the dead to fight for them.
The "Alliance", a human faction has overtaken the galaxy in Firefly. In Mass Effect, the "Alliance" is the human space military and exploration force.
In Firefly, the character River was raised in a military training school for children with special powers. In Mass Effect, Jack was raised in a military facility for children with special powers.
This seems to link Firefly and Mass Effect. Do they have a shared creator or writer? Or is there some other link? Or is this just a case of influenced ideas?