Perfect Playground came as a surprise as it almost feels as though it functions as a continuation to the first half of the main theme, prompting another departure in expectations. Well arranged throughout with some sense of ambiguity in where its headed and what kind of tone it wants to set.
Digital Parasites makes no allusions as to what it isn't - it has a rather ominous feel to it in the first half. Meandering along, bathing in uncertainty. The half-way point comes along and the overall tone turns much more oppressing, as though the player has been spotted or is now actively being chased. Choice of synths here is interesting - plays back into the ending of the Main Theme in regards to active degradation and corruption.
Finally, End Credits cuts straight to the point with the tone. The chase has come to an end and it doesn't seem like a good ending for the player. I like the various glitching effects in this, from the thoughtful use of stuttering to the layered, distorted bell-like tone of the snare and the noise bursts.
I think my favorite of the four may be End Credits - it is unapologetically intimidating. Everything was arranged really well and I enjoyed the dark tones that are omnipresent throughout the mix. Great work. :)