What it is
Sun Dogs is an "art project" of sorts disguised as a video game. It is set in a post-mortal transhuman civilization; that which used to be mankind is now consciousness, backed up by a "cortical stack", that inhabits a "sleeve". Sleeves can come in many varieties and shapes, including a non-humanoid arachnid-esque frame for those that feel particularly spider-ey. Anyway, civilization spans all across the solar system (not including or beyond Jupiter. So I believe five of the microplanets if you include Vesta, in addition to the known planets and moons.) You are an inhabitant of a "sleeve", with a space ship. The planets, locations, and yourself are represented as circles orbiting the central axis in what is a two-dimensional representation of our solar system.
The extent of the "gameplay" is merely pressing one singular button; interact with the given environment that you currently occupy (say, if you're at Vesta for example, you can hit the button to explore or interact with Vesta.) Every time you hit the button, you get a short wall of text with a little snippet of lore from that region. You can occassionally acquire items and sleeve upgrades from hitting this button, which can be used in interactions to unlock secret lore snippets only available from that sleeve upgrade or possession.
That's it. That's the game. You fly around to different planets and get lore. However, occassionally interactions will kill you. After I believe six deaths, you die for real, and the game ends.
Review
It's a very interesting and well-executed "game" (more of an interactive art-piece, really), but it's not worth the $10 the creator charges for it. I do not regret having played it; I enjoyed it a ton. The lore was good and it's an interesting and fleshed-out world (or, rather, system).
I say it's not worth the money because I only got 3 hours of gameplay out of it (across a few playthroughs) before I had consumed like 90% of the lore, and the remaining snippets would be so obscenely time-consuming to access (considering you have no idea what planet or item/upgrade you need to get it, it's just blindly pressing the interact button). I generally tell myself that there has to be at bare minimum one hour of enjoyment per dollar spent; an interactive novel that I can get 10 hours out of is worth 10 bucks at most (which is why I say at bare minimum). That's just my own "opinion", or whatever you would call it.
You can pick it up on Itch.io or Steam. The Itch purchase gave me a Steam key, so I would get it from there (that way you have it in two places). If you like, though, you can save a few bucks if you get it from here