I do a lot of searching for indie games and other less known titles to find the rare gems. Here are a few worthy mentions that I’ve found: Hacker Evolution Duality, Evochron Mercenary, Bastion, Defcon and Limbo. Most of these are available on Steam.
Hacker Evolution Duality is a “hacking simulation” that’s not exactly realistic but is still interesting, fun and unique. You break into other systems, use compromised systems to bounce across and raise trace time. You must act quickly before your traced and as multiple AI systems attack you.
Read this review from NeoWin.
Evochron Mercenary is a free form game similar to Freelancer. You create either a miner/trader, combat pilot or racer. You can trade commodities, battle other ships and asteroids, seamlessly fly into planet atmospheres, mine asteroids, planets, build new customized ships and space structures. The avionics are somewhat complex, allowing you to switch between IDS and inertial, allowing you to either drift and save fuel with small adjustments to your course or travel under engine thrust. I definitely recommend this game if you’re a fan of open games similar to Freelancer.
Read this review from GameArena.
Bastion is an original action role-playing game set in a lush imaginative world, in which players must create and fight for civilization’s last refuge as a mysterious narrator marks their every move.
Read this review from Joystiq.
You play the role of a military Commander hidden deep within an Underground bunker. Your mission – to successfully exterminate your enemy’s civilian population whilst disabling their ability to attack your own. Start by launching your battleships, subs and bombers in order to decimate your opponent’s defences.
Read this review from CPUGamer.com.
Uncertain of his sister’s fate, a boy enters LIMBO… that’s about all you know in the beginning. Limbo is beautiful, simple, mysterious, foreboding and addicting. It features refreshing puzzles and atmosphere.
Honorable mentions: Amnesia: The Dark Descent.