Unfortunately, specific details about what the game actually is are thin on the ground so far - no screenshots, concept art, logos, suggestions about what the game may contain, or even what formats it'll be on - but there are a few educated guesses we can make about what First Assault may be. The first, and the one we're hoping is right, is that it could be a sequel (prequel?) to an old Star Wars game called Star Wars: Rebel Assault. Released in 1993 on the PC, SEGA Mega CD, and 3DO, Rebel Assault used a mixture of 3D graphics and FMV video to rather stunning effect, creating a game that, at least to our eyes, didn't look that far off the films at least the time.
With a mixture of missions set on foot, and those that saw you flying spaceships, Rebel Assault sucked you into the Star Wars universe like no other game that had come before it, with accessible, arcade style gameplay that saw you mostly moving targeting cursors around the screen rather than flying ships for yourself. It did well enough to earn itself a sequel, the imaginatively titled Rebel Assault 2: Hidden Empire, which carried on much in the same way, providing fancier still graphics, cutscenes using real actors, and a storyline which filled the gap between A New Hope and The Empire Strikes Back. While a sequel to these old games may be unlikely, it's something we'd love to see happen. Star Wars games have been needing to find their roots for a while.
On the other hand, the more likely suggestion is that this could well be Star Wars Battlefront 3, just with a new name. A team based shooter in the style of the Battlefield games, Star Wars Battlefront was a multiplayer-oriented, online game that saw teams facing off against each other to capture and hold various points on a map, which would then begin to drain the other team of points. Battlefront 3 has long been in development at Nottingham based Free Radical, but hit developmental difficulties when Lucasarts inexplicably pulled funding. Free Radical closed down (and are now owned by German company Crytek), but Battlefront 3 remains at large, with rumours having spread recently that the game's development has been passed to another team, meaning a re-announcement may be on the cards. Still, it'd be odd if the developers scrapped the fairly well known Battlefront game, and went with a different moniker.
Either way, the chances are we may not have long to wait to find out exactly what Star Wars: First Assault is - the last Star Wars game to be announced, Star Wars 1313 went from being rumoured to being unveiled in less than a month. Hopefully, we'll know how we'll be blasting back into a galaxy far, far away in a few weeks time.