I'm working on a zero bot, but so far it wouldn't be able to survive in your sim, and it only rarely sends out any viruses.
So far it's at 25% F1 conditions with 50 alge. I'll post it when it get's closer to regular F1 settings, currently having problems with big titans killing half the population because waste isn't working properly and the field is so small. That and alge that get onfected with a large chunk of dna, making it shoot and produce poison and shell.
The alge can't reproduce because of the veggy repop settings, since F1 settings allow veggies to get too strong, with the high energy gain and low cost of poison and shell. But I haven't managed to do anything about viruses. I'm thinking of using a different veggy, one that keeps it's code clean from viruses and maybe kills off bots with too much waste. Just wanted to use a zero bot as veggy to make sure some virus didn't accidentaly spread handcrafted code into the zero bot. I guess if the alges virus defence is strong enough it shouldn't be a problem, but you never know...
I don't think increasing the sim size would help much since waste doesn't kill off the big non reproducing bots. And they're preventing the zbot from achieving a larger size, I see it trying, but then some titans come along and kill off any bot large enough to get hit...
And the bot needs to get larger for me to increase costs any further... been killing off the big bots manualy so far, but getting real tired of it.