You basically can alter the plague names, put specific stats, names, requirements, images and description for a plague and its traits, chance various stats about a country, tap the deepest you can into the mechanics, though there is still stuff you aren't allowed to, for istance setting an event to repeat itself in a set amount of time(there is only a global turn counter wich you may lket it reset or not by the events). The main limitations are in the base template of the plague, as there are events that just can't be taken away, such as the one for the first Gen-Sys lab getting destroyed, also some names are still unable to be changed, you just cannot change sounds in any way, and it is a chore to find away to make your own (standard) ending that doesn't say "PAX-12 to destroy humanity" as usual, but I dunno if you want to know how to do it. Thern you can give an alternate victory that just wants you to infect all people and have a specific trait you can choose activated, you can easily personalize this ending, unlike the standard one. You can change as well the governament actions but that is pretty limited, though you can still do stuff such as preventing a country from doing cure research with a trait evolved, though you can just use the events and have more possibilities with that.

Ah well, at least someone responded...was hoping to do something where instead of being the virus you were the source instead.

the source of what, exactly?

...the virus...lol