Wow, haven't used my GMC account in like two years...
A friend linked me to this game the day of its release. First and foremost, I want to say that, at least in my opinion, this is an
amazing game, and I do not throw that term around lightly. In fact, I'd go as far as to say it's one of two or three freeware games I've ever played that actually managed to impress me. The gameplay and controls were superb and the storyline hooked me in. I've never before seen a platformer that allotted such freedom to the player; I beat it with something like 14 kills and never once picking up an ammo-using weapon, and have already began a second playthrough, this time as a heartless, homicidal maniac.
However, there were a few aspects to the game I felt brought it down. Hence, the rest of this post is probably going to sound horribly negative, even though it's just an in-depth analysis of a few small aspects. For the record, I am an incredibly critical person who always feels like almost everything could be improved
The dialogue - beautiful towards the end - felt forced or awkward in some places. In particular, I'm not sure I liked the way in which the features and controls were explained in the first level. While breaking the fourth wall is clever in a few places (that logbook where the alien wonders what a pause menu is comes to mind), being told "Press Z to kick" does not help the game's immersion factor. Up until the first boss or so it's even somewhat unclear whether than game is even trying to have a serious plot or whether it is just trying to be a standard jump-and-gun with an "aliens are attacking" premise.
The player
does need to be told how things work, but in my personal opinion this works best kept out of dialogue. A lot of games get around this by showing a small image of the proper key to press, or a tiny bit of text like "Z- kick" while the dialogue says something realistic that still explains the connection (such as "kick this door open"). While I can't speak for everyone, I personally found it odd how the opening bits were a mix of realistic, even dramatic dialogue, and things that openly acknowledged that it was all just a game.
There was one bit of text at the beginning I definitely didn't like: "These guys have also gathered stolen Komato weapons, for which you need 'Komato', but that's for later". Acknowledging the existence of control buttons is one thing, but here he is openly showing knowledge of future plot events. Saying something about how Komato weapons are mostly stored in other sectors or she isn't yet strong enough to handle them would accomplish the same thing without having your characters knowing more than they should.
My main criticism of the game, though, is its color usage. With all graphics, your goal is to convey as much information to the player as quickly possible. At the most basic level, your graphics do this fine; bigger enemies are tougher, leaner enemies are faster, and so on. While you didn't necessarily use color
wrongly, it definitely wasn't used to its full potential.
For instance, a game I feel has excellent color use is Half-Life 2. In Half-Life 2, explosive barrels, hopper mines, activated grenades, and gun turrets all have one thing in common: the color red is somewhere on them, bringing attention to their danger. While the player doesn't actively think "I see red! This must be dangerous", the lack of red elsewhere in the environment means when the color red DOES appear, it grabs the player's attention. When you see a crowd of zombies and one pulls out a grenade and rushes at you, the red light from the grenade separates him from the rest of the crowd and lets you know that HE is your number one priority. Likewise, when you are hiding behind a barrel for cover, you instantly know that you shouldn't hide behind the red ones, because they will explode as soon as someone fires at them.
For comparison, here is a screenshot of an explosive from Iji.

At a glance, the first things that stands out in this screenshot are the orange crates, which do nothing. The explosive has
some identifying characteristics, such as the yellow caution tape, but gray and yellow do not significantly stand out from the platforms that make up the rest of the environment. I didn't even know that it was an explosive until Iji outright said something about it and referred to it as such.
Now, imagine if the explosive was colored differently; maybe it was a brighter yellow, or maybe the caution tape was red. All of a sudden, it stands out from everything else in the environment. I'd probably shoot it right away just because it looked so different from everything else. This may also lead to me using them more frequently to my advantage, such as shooting them when an enemy is by them, and less frequently hurting myself on them when I think they are just a regular decoration block. While blending in with the environment might make it FIT better, it does not emphasize its importance. There is an important middleground where things fit together nicely, but the important bits are still more obvious.
Color use could also help better differentiate the alien races. For instance, here's a shot with two races of aliens fighting:

Looking closely, it's pretty easy to tell the two types apart: their anatomy is entirely different. However,
at a glance the one that stands out as different from the rest is the purple alien. Similar colors and shades are used on the armor, skin, and weapons of both alien types.
Also, there is an aspect of using color for setting the mood that I feel was only partly taken advantage of. When it came to lighting there was no problem at all; the way the screen darkened at certain parts added a HUGE emotional impact to them. However, I didn't particularly like the way hues were often indiscriminately mixed. Like, on the screenshot on the first page you have cold shades of blue inside the building, warm, dry oranges outside the building or on the crate, and a somewhat warm, dark maroon making up the walls. While it doesn't look
bad, it's not entirely clear what impression the colors are meant to convey overall.
Not to say you should stick to one color, such as falling into the "brown = realistic" ideal of most modern games. Rather, it's important to be conscious of the dichotomy you create between various colors and shades in an environment; much like how a less common color can be used to draw attention to important items, mixing two colors will emphasize their differences. Half-Life 2 used incredibly conflicting colors in the environment; warm, natural shades on the run-down earth buildings looked nothing like the cold, dark, metals that made up the alien structures, but this only helped to demonstrate the way the aliens had been replacing the buildings that were originally on earth.
Of course, I'm no professional expert in color use, these are just my personal observations and opinions (I'm busy trying to convince all my friends to play this game so I can see if they agree with me or not). However, if I had to pretend I was an expert and give advice, I'd say it's important to at least consciously pay attention to how you use colors and what they make the player think or feel.
But yeah, those are my only real criticisms. This game is amazing, and I would pay money for it if it was being sold for money. Is she actually saying "sorry.." the first few times she kills enemies? That's awesome. And the credit music is PERFECT; it is the perfect closing to leave the player with a good aftertaste.
As prior posters have said, I hope this game gets the attention it deserves. I'll definitely spread the word to people I think would be interested.