As the gods have an automatic sense spark (thus sense all supernats) within one mile and I only saw dragons have a special rule there that they can hide themselves. Is there any possibility as to how spark holders (gods, puks, ...) can sneak up on gods?
Jut saw an answer to a similar question from the makers of the game on their forums.
In essence you can sneak up on another god. The spark sense is more like the highlanders' sense (from the series). You feel something/someone is nearby but don't know where or who it is. Like in the series you can look around and try to see if someone else is looking around too (thus in a crowd it can be quite hard to figure out who you are sensing).
Additionally, with there being more spark carriers (including supernatural beings that are not gods) than highlanders in Highlander it will be more often that you just ignore that feeling.
Thus in sum: It is possible to sneak up on another god... at least if you are not the only living being around. (And at least if the other one does not have the same dominion, as then they can pinpoint your location.)
The developer's own words on sneaking up on fellow gods:
Just because you know there is someone with a Spark within a mile, it doesn't mean you know who they are. If it's just you and one other person within a mile, then you do, sure. But in a major city, you just know there is a god nearby. I'd say it does have a highlander effect, however, in that if you lock eyes with another god you know what each other are.
[…] Depending on how much traffic a god has through their territory, they may become paranoid if they just start getting paranoid every time they sense a spark entering.