We're topping out the casual charts on Steam in the top slots, and the family games and indie games in the top 4, and in mac games in the top 10 overall, but that said it's still early days for folks picking up the game. In a lot of respects this game came out of nowhere in the last four days, and sales are trending steadily upwards, but this isn't yet at the stage where there are hundreds of people playing online yet.
Also, one thing I found with AI War was that only about 10% of the players actually wanted to play multiplayer at all, and most wanted to play with friends rather than looking for games on the internet. Out of 25,000+ players for AI War, only ever a hundred or fewer have ever been asking for other folks to play with on the Arcen forums or other forums that I've seen. With a puzzle game, the casual players buying this are even less likely to go looking for internet games, so I expect we may see that skew even more to the lower end.
That is disappointing, but I think that as the game picks up momentum over the next weeks and months, we'll see more people being around online.
Oh, and by the way, on the subject of the multiplayer listings specifically: one challenge with a system like this is that it's exactly two player, right? So if there is one person there hosting a game waiting for someone else, and then a second player comes on and connects to them, then both of them disappear and are in game. Person three comes and sees no one. Person four comes and connects to person three, and then person five sees no one, etc. So the only way to have a lot of people on the list is if there are a lot of poor matches that people don't want to connect to (as can happen), or if there's just a lot of people posting games at the same time. I still think that the main problem right now is that there are too few players at this early stage, but even once there are more players I think the number of concurrent games waiting for players would be vastly less than the number of games actually in progress, and the latter are invisible. Thinking about a lot of the DS games that do auto-matching (Planet Puzzle League and Mario Kart DS), it strikes me that they might be prey to much the same mechanic, which would be why they do that auto-matching (that I detest, and which takes forever). They might have been trying to dodge the inherent empty-seeming nature of server listings in games that are 2p-only.
So even if there are hundreds of players playing online, the server listings might still look pretty empty because of that above phenomenon. Right now it's mainly that it's early days, but that's something to bear in mind.