I have this on my Android Phone. I really love this game and I want to experience everything so I'm willing to pay. However it's somewhat confusing. I want to pay to have everything but I want to pay the least possible to get that. Also I don't want to pay to unlock stuff that can be unlocked by doing certain things ingame.
Currently I have beaten from Bacteria to Bio-Weapon in both Casual and Normal. What else can I unlock by playing (and how) and what do I really need to buy to get everything the cheapest possible way?
I might be wrong, but you can unlock Neurax and Necroa by getting at least 3 stars on every normal disease while playing on brutal.
Beat every standard disease on Brutal (doesn't matter what score) to unlock Neurax Worm.
Beat Neurax Worm on Brutal to unlock Necroa Virus.
Cool, I'll start beating the standard diseases on brutal, already did on bacteria.
What about paying for content? What can I only get by paying and I do I get that for the cheapest possible?
You can only get scenarios by paying. If you liked the Black Death plague I'd recommend buying all 18 for 2.99, otherwise each is 0.99.
I don't recommend buying the Plague Pack. It gives you nothing new except for scenarios if you've already unlocked Neurax and Necroa. It doesn't unlock genes or cheats, which makes it kind of useless.
If you have bought the full game on Android, then the only bit that you cannot unlock by playing is the scenarios. As dragon55 says, beat everything on brutal and you will get the majority!
I have beaten every normal disease in casual, normal and brutal and that didn't unlock anything for me.
So far I haven't bought anything. I wanted to buy the scenarios but stupid google wallet is having problems with mbnet (virtual credit cards). I had used them in the past without any problems but now they're not working.