Ah, I see what your problem is with the skins: you're in the wrong section! It's not in shop, its in unlocks XD
I'm gonna try to touch up the main menu pretty soon
Oh, ha ha to me then XD; on that note, I believe the problem with me not noticing it is that I thought the word 'Unlocks' was part of the game's title, due to the font not being consistent for each of the Menu items, as so:
Anyhow, I see I had managed to unlock all the skins :D
Aside from that, it occurred to me that the game sound more like it's occurring in an abandoned hospital (due to a patient showing some slight improvement in their vitals), or an experiment in a laboratory :p
Other than that, the fifth line of the Ending scene text seems to be incomplete, 'But Sir, some of the values have...' (or not?)
Also, the amount you have left doesn't display when you're fighting the boss, there's no visible indication as to when you've been hit, while the text that displays what level you're at, the amount of gold and points you have, your highscore, the boss's HP as well as your remaining HP are almost invisible/blended in with the background :p
Also, I can't select the 'Brilliant Overload' skin despite having unlocked it, and the Skins can only be selected when you hover the mouse cursor over the the title of the skin, instead of the full line :o
Other than that, while I've discovered the amount of Gold you carry does accumulate after each game (as in, you got X amount of gold in one playthrough, died, start over, get more gold, die, and you have more gold to spend :) ), it does not increase beyond 4 (maybe due to no more gold being spawned to collect etc?), making it next to impossible to acquire the Pointless Book :/
Edit: Never mind, I managed to accumulate enough Gold in order to purchase the Grimoire, which gave some insight as to what to do to get that last achievement, and also, clever use of the names Thomas and Jefferson (& that reference to 'Lord of the Flies', which I kept forgetting about XD)