I feel that the best way to describe the aesthetic of this game is as follows: Imagine that the computers used to render the graphics which portray the horrible, gritty world overrun by machines in the film The Matrix were corrupted by a hacker who replaced most of the textures with imagery from Peanuts comics. This is the imagery rendered by the prose of this game. And yes, you do need to have read a moderate amount of Peanuts to recognise the iconography, and knowing The Matrix some will also help. I guess The Simpsons anticipated all of this with that poster outside the Googleplex which says 'You're in the Matrix, Charlie Brown!'
However – I am already struck by the difficulty I feel in describing this as a game. Perhaps it is in the area of pieces like this which the term Interactive Fiction will come into its own in a more literal sense. Mastaba Snoopy is a poetic prose story with junction points which determine what may be read next, but there's a low sense of consequence based on what you click – I confirmed this at least for myself by repeatedly rolling back one move, trying the other option(s) and seeing if my feeling about the whole moved a different way as a result of what I read there. It didn't, except at a handful of major branches; there's a kind of uniform forward velocity into this clever concoction of an alien meets future-internet world based on Peanuts comics, no matter what choice you click on, but I can't say that the different facets of it feel very different to each other. The world is rendered with effective writing, and the immediate effect of the piece is different to that a static piece of writing, but the combination of the piece's overall abstraction and its low consequence of action mean that its emotional effect is still closest to that of a static piece of writing, albeit one which can be rotated to be viewed from a few different angles.
Peanuts has always been and will always be a big part of my life through all of its sense of humour, writing and artwork. I doubt I missed any of the numerous references in Mastaba Snoopy, whose whole world is built out of an alien's interpretation of Peanuts comics. Some of the iterations are darkly amusing, though nobody is likely to guffaw at the bleakness of the whole. Coming into this game as a Peanuts guy, my mental state was along the lines of, "Alright, bring it." I came out disappointed that Mastaba Snoopy was neither specifically as humorous nor as thoughtful enough about ideas from Peanuts as I'd hoped it might be. It's probably hard to be specific when you're also being abstract. I didn't feel that any more meaning emerged from the throbbing of Snoopy's loins – a scene in Mastaba Snoopy – than it would have from the throbbing of, say, Hello Kitty's loins. Or rather, both may be saying the same thing (whatever that is). Mastaba delivers a fair bit on the cyber/veneral imagery front in general.
In spite of the quality of the writing, I was disappointed re: Peanuts and I missed the presence of more game-like consequences which might have made me get more into this world. If the writing alone is enough for you, you may like it a lot more, and the whole idea is very imaginative.