Mothership is a sci-fi survival horror trpg set in an eerie cosmos. If this makes sense, it feels a little like an OSR Call Of Cthulhu being used to run Alien. Gameplay is technical, there's a bit of crunch to the rules, and play is scenario-driven. There's also plenty of room for players and GMs to get creative with the tools the book gives them, and the mechanics don't feel intrusive.
Breadth-wise, the PDF for Mothership is 44 pages, and there's a *lot* of support for it. There's adventures, third party expansions, the fruits of a successful crowdfunding campaign, and more.
The layout is also clean and immersive, and the art does a great job of anchoring the game's stark and creepy atmosphere. There's even a character sheet that'll walk you through creating your character---which is an extremely nice touch.
Mechanics-wise, Mothership is a d% system. You have Classes, Skills, Stats, Saves, and other familiar landmarks, but core rolls are d100 under a stat. Skills, tools, and situations modify your success chances---and if you're rolling against someone, whoever rolls higher without going over wins.
Combat is simple and direct. You make a save to act first. Everyone gets two actions per turn. You roll an attack and the defender rolls a save to resist it.
Of note, the player characters are often as much a danger to themselves as anything else in a given scenario is. Fumbling a roll, making a bad judgement call, or accumulating enough Stress points and Panicking are all things the players can easily do, and they can result in accidental weapons discharges, ship damage, or other small disasters---which can cascade. Seeing a character die, or panic, or damage the ship can cause another wave of rolls, any of which can make things worse.
Under good conditions, players can take steps to keep their stress low, their health high, and their rolls advantaged. But outside of good conditions, luck plays a pretty significant role.
Resources-wise, the book has weapons and armor and equipment and potential skills. There are also lists of mercenaries, colorful trinkets, rules for ship-building, and a pretty granular exp and leveling up system.
Overall, if you're looking for a space horror game with a slightly technical feel and the possibility-but-not-guarantee that you'll survive against the monsters and horrors of the vacuum, you should pick Mothership up.