OP Impressions!
Pale
Interesting take on the exploration genre. Its just a small game, but the main mechanic works rather nicely. You get a limited amount of light sources and need to use them strategically to light the area around you, allowing you to find the way between the different "checkpoints". I found it interesting how I adjusted my line of thinking depending on the surroundings and amount of light sources I have left.
Pocket Robots Test Chamber
Some others wrote about it already, but its a very smart programming themed puzzle game with some clever puzzles and smart additions/variations. The presentation is a bit.. lackluster, but its a fun and very intelligent puzzle game. I bought the game for my mobile phone to play this on the go actually

Simple rules, hard to master. Lovely.
QBEH
Not bad for a 3D puzzle game, but its missing the originality and wit I've come to expect from these games. Sorting around cubes to make platforms to jump on is neither original, nor interesting. I only played the prototype of this, but it didnt leave a strong impression. Replaying a level for 10 minutes because you cant hit a cube that you need to jump on is quite annoying, but even despite those issues, its competent enough for what it wants to be, just not good enough to warrant more play time unless someone else tells me that QBEH-1 does a 180° turn and became way more interesting.
Spectrum
Platforming puzzle game in which you need to explore a level, and use color beams to change your own properties, which in turn allows you to pass barriers for those specific colors. The game works (even though I just had my first Unity crash ever with that game), but I dont appreciate the way how the gameplay is set up. Look around the level, search for light sources, find a way in which you get from one light source to the next, open door, repeat. Its cute how they added some "stealth" elements basically, but the game might just not be for me, even though its technically sound.
Sub Commander
This game is incredibly intriguing, being basically a hardcore version of FTL with Roguelike ideas for a submarine simulator, including random events, fights and missions. While this sounds incredibly enticing, there is also quite a big barrier to actually start playing the game, and once you started playing the game, there isnt much... game there yet. You have tons of options on your boat, but no real goal/missions yet other than reach X, defeat Y, which "works" in itself and gives you reasons to take care of your boat, but it really needs more of an ingame guide to ease players into its mechanics. I really love the direction this is taking, but lets say I only call it "recommended" to dive into and experience a rare species of Indie games in which realism is king, not necessarily to play it though. After reading and playing around with it for 2 hours, I appreciate the direction, but it still needs more "game".
SubRay
Good underwater exporation game with shooting and light tactical elements. I love the art style and animations and the general gameplay. Unfortunately, the game crashed for me twice, so i needed to restart once and couldnt find enough motivation to play through the admittedly slow beginning again. Neat game in any case though, definitely one of those prototypes that would deserve a fully realized version with more content and less crashes.
Substratum
Interesting puzzle game in the vein of Starseed Pilgrim and Fjords in which you need to figure out direction and rules yourself, but less.. polished? The game doesnt seem to do a good job at informing the player what he can or cant do, but this game is way smarter than it seems at first with some interesting and VERY challenging puzzle mechanics. The game would definitely benefit from a better presentation, but this game is surprisingly good. One thing you need to remember though: You can definitely fuck up a level completely, and pressing reset will bring you back to the moment when you entered the screen. However, if you already changed screens, your fucked up solution might have been saved, in this case press the reset button multiple times.
Tales of Maj'Eyal
This game is, and I am not saying this lightly, the best roguelike I've ever played. I love these games, but the way the game is structured, how the mechanics come together, the incredibly satisfying loot improvement curve, the way how most characters play fundamentally different and just how much stuff there is to find and see... is mind boggling. The initial release was an older game, but its still frequently updated, so I'll just honor it by including it here again. The game is not super pretty and screenshots might not be overly convincing, but its fan-fucking-tastic. If you need a more in-depth writeup, there you go:
http://www.neogaf.com/forum/showthread.php?t=853003
>----------< Highly Recommended >----------<
Tales of Maj'Eyal
Crimsonland
Chronology
Lantern Forge
Pocket Robots Test Chamber
Baby Mummy's Curse
>----------< Recommended >----------<
Monochroma
In Between
Substratum
SubRay
Hardline Gunner
Pale
Sub Commander[*]
Mother Machine
Chained
Arcade Ace
>----------< Decent-ish >----------<
Lurking
Spectrum
Crawle
Instant Dungeon!
Cyberpunk 3776
Arc
QBEH
Nekro
Fignermukcre
Iktsua
Composition 83
Beret
>----------< Bleh >----------<
Antrosoma
Forsaken
[*] Recommended to check out, but dont expect much game yet.