The blood creeping in effect is quite cool, but it does make the game a bit difficult to play when you don't know what you're doing. On perfect runs, it's purely cosmetic and barely worth noticing. A way to punish recklessness I suppose and make the game more puzzly. The spikes are actually somewhat clever in the way that they circumvent softlock situations, but because they're all hidden-block style, it does make them a bit annoying at times, but it does open up some opportunity for mastery where in replays you're constantly avoiding hidden spikes and bad paths that would kill you if you didn't know which way to go already.
The cat room is obviously the best, and while I'm not so sure about the rest of the game, the cat is certainly in a box (because of course the cat is in a box, silly cats.)
Fun game! XD.