It seems the developer of Blade Symphony [Steam] has had a case of feature-creep and so the next update that was due with Linux support is going to be late.
It was due to arrive on April 12th, but on that day the developer posted this announcement on Steam instead. What they're essentially saying, is that they didn't have enough people for everything they wanted to get into the game, underestimated the amount of work involved and ended up with feature-creep (constantly adding more and more).
A shame, but it's good to know they're not having major issues—well, I wouldn't say it was that major, just a case of getting it finished.
They say in the announcement that over the next three weeks, they aim to get it done. Additionally, they're looking for a developer to assist with "source development" (it's using Valve's Source Engine) and Linux support is still fully planned for both the game and the server.