I tried building a better version of it, which turned out to be very unstable (you may notice some unwanted behavioral problems with the queen.) The I lost the last stable version and lost interest ...
...anyway, I found making multibots so much more fun, and started working on a branching one (Hydra is the strongest one so far I think). Then I stopped for about a year as I went into study overload, began writing my own 3D fractal generators which kept me busy for ages (Hypercomplex numbers have hundreds of vague and arbitrary definitions), and recently rediscovered DB. I tried making a good evosim which has never previously worked for me, but now that you mention it, I might try and fix this bot.