I agree with GamerKingFaiz on his assessments of the games he had played, so I'll just comment my thoughts on the ones he hasn't:
Aquaria - Sort of like Metroid in gameplay and Ecco in setting. You also learn songs that do special things, so a little bit like OoT. It's pretty fun and has great style.
Cortext Command - I only played the tutorial, but I'll say it was kind of difficult with my laptop's touchpad. It seems to be a 2D shooter that takes some strategy.
Gish - A nice enough platformer, but I feel like it has been outdone by every other indie PC platformer that's been notable lately (that is, I liked Braid, VVVVVV, And Yet It Moves, and Super Meat Boy all much more than this game). You play as a tar ball who makes it through levels using his ability to squeeze through small holes, bounce, and pack himself together to become heavier.
Lugaru HD - I couldn't really get into this one. It's furry art design, dark story, and confusing controls combined into something I just didn't want to play. I should give it another chance. It's set in a fully 3D world with an emphasis on real time close range combat.
Penumbra: Overture - My favorite game of HIB #1 because I love horror games. This one has a more physical world than something like Resident Evil where you just click on an item to use it. There's stuff like moving things around with your mouse and blocking doors to make sure you're safe.
Revenge of the Titans - I didn't play this one much yet. It's some sort of strategy game where you build things to fight of approaching hoards (is that a tower defense game, I don't know).
Saromost 2 - I thinks it's a point-and-click adventure like Machinarium, but I found it's puzzles to be tougher, so I haven't played it as much as Machinarium (that is, I haven't touched it since the day it was originally added to the HIB #1 last year).