Despite Unvanquished being out for more than 3 years, the servers are still empty most of the time.
I think the reason is simple and obvious but is being ignored and denied: the game doesn't scale down. I mean, seriously, the game is obviously meant to be played with balanced teams with at least 5 players on either side, but how do you expect the game to gain a player base necessary for such games to happen regularly if the game breaks down at low player counts and especially at 1vs1?
You can't defend at all while you're building, you can't not build and simply use the default base because default bases are usually incomplete and can't survive a single attack. Aliens have to waste morph points to go back to the builder form and have to re-build their base when advanced grangers become available.
You can't take risks, especially when playing against better players, since you have to finish kills to get credits. And if you, for example, revert to a dretch while the enemy has a Lucifer cannon... have "fun" watching your base die... or have "fun" trying to get past the turrets and waiting for free morph points.
I mean, with such a small player base you have no choice whom to play against, so the game should still be fun even with unbalanced teams or unbalanced 1vs1 and not instantly devolve into "You rifle, I tyrant". The weaker side should at least be able to build a base.
And 2vs1. There's always a point where a game is 2vs1. It should be fair, not unfair.
Also, the first launch experience, where you have to unpack the right nested archive the right way for the game to work. Like here. Or here. Or here. I mean, I know that you're working on a proper solution, but still, there is an easy temporary workaround that would solve a lot of the first time user's problems: don't pack the binary directories into ZIPs, make Daemon search the parent directory for 'pkg', and, even better, add simple launchers, Unvanquished.exe and Unvanquished-Linux, to the archive root. The launchers should determine whether the machine is 32-bit or 64-bit and launch the correct Daemon executable. I mean, ZIPs within ZIPs don't even reduce the download size that much.
When connecting to a server, the game doesn't check if the server runs the correct version of the game. Instead of telling the player to update the game, it just crashes most of the time.
And the bots. Sometimes the bots can be very effective, but most of the time they simply waste credits and morph points. They get stuck everywhere and don't have any failsafe (eg. bots could start moving randomly if they can't find a path to an enemy and respawn if 20 seconds of random movement don't help it). They don't build so you can't play a normal game against bots.
There's nothing to do while waiting for other players. I mean the training server was the best thing that happened to Unvanquished, but even it wasn't fun: no balancing, bots got stuck deep inside their bases all the time so you couldn't earn credits/morph points.