Monday, March 29, 2010

Zombie Farm

[UPDATE 7-17-11]
Since apparently this post is still found quite frequently, the Zombie Farm Wikia (which I started but no longer maintain) has a great page for Levels. Peace be with you, Zombie Growers.

When I got my iPod Touch 3G, I promised myself that I wouldn't buy that many games for it. I got a new iPod because I love listening to music and my old one died and I decided to go with a touch instead of a classic because I was using my old Palm Zire to keep track of school assignments (because using a paper planner really wasn't working out for me, but that's a whole other story) and I figured there's gotta be at least one app out there for doing that. I didn't really get it for games because it's not a gaming system. I've had many handheld gaming systems over the years (although most of them are ancient by now) but the iPod touch just isn't built for gaming. Plus, I know that most of the good games cost money and I'm really cheap.But anyway, one day I was bored and I can't remember how I came across it, but I found a little game called Zombie Farm. I can't even remember why I actually downloaded it since I despise people who send me neighbor requests for farmville/town/place on Facebook, but I guess it was because it's free. I didn't play it for a few weeks, just had it installed, until one day work was especially slow, and I needed something to do. So I started farming. And I've quickly become addicted.

I'm not going to talk about the game like pros, cons, what you can do and all that. It's pretty simple. You can plant both crops and zombies, get upgrades, veggie mutations, decorations, and (best of all) you can invade other places with your zombies.

I think the funnest part for me is partially the whole math aspect. Maybe it's the Calculus courses I've taken, but I take a look at the different grow rates of the plants and think "What I wanna do is maximize profit while minimizing time/risk." I'm even so (aspiringly) nerdy that I made up a spreadsheet to calculate stuff like that.

Just the math behind the numbers and all is pretty interesting to me. Like it's better to plant crops that have a higher cost (risk) because if it is fertilized (which is random), it will not only yield that plants profit (like 17 for the Venus Fly Trap) but also pay back the entire cost (like 120), which gives you a much higher rate of profit than even if you planted something that grows faster and has a higher profit but is unfertilized.

Another interesting math deal is the whole levels/experience deal. I'd never really thought about it before, but in my youth, I'd played Runescape and the original Pokemon Gameboy games, both of which have experience ranks. I looked into both of these and found that they did indeed have equations that determine what the experience is at each level. Here's both of em (Runescape first, one of the Pokemon second):

Apparently Pokemon has a few different equations depending on the Pokemon, but (in terms of the first generation of games), the one above is the most complicated. Another one is just EXP = n3, which is extremely simple. That's why it really surprised me to find that Runescape's was so much more complicated. I mean, it's got a summation, two's just bizarre (to me, at least). I really wonder where the game developers got these equations. n3 seems like it could just be picked because it was a good rate, and the more complicated Pokemon seems like it could just be integrated from a defined rate of change. (....Ok, I have no idea what I'm talking about, alright?)

So anyway, I was curious about Zombie Farm's experience/level relationship, partially because I wanted to know what my next level would be, but also just curiosity. But the more I look at it, the more it looks like it might just be defined values instead of an equation they derived. Why? Because level 16 was 5500exp and level 17 was 6500exp. That seems a little too convenient to be from a formula, but maybe I'm wrong. Plus, couldn't you reduce it to a formula anyway?

You'd think with me being in Calc III I'd know how to do this stuff already, but oh well. The most I can figure is that if it is indeed an equation, it must be something along the lines of E(L) = floor(L3.1), which seems entirely arbitrary. I was thinking it would be so freaking awesome if it was E(L) = floor(Lπ), but unless there's some constant somewhere, that doesn't add up. It might help if I had more info than the experience for two levels and the fact that I think you start with 1 exp at level 1.

Anyway, it's extremely fascinating to me, considering the fact that everything that happens in the game is just math. Calculating how long the plant has been growing and then ripening/wilting it depending on the result. I actually had some plants overriped the other day. Some glitch in the game made them keep growing past their harvest point, so it read as "-19% grown", but it somehow still said "38 minutes left" or some such, and after that time, they grew and I harvested them. It was bizarre.

May your invasions give you many brains,


  1. This comment may be a little late and you may have already figured everything out to do with the levels, butit can't hurt to say.
    I've been playing Zombie Farm about a week or two now, and I've noticed that once you get into the higher levels the patern for experience points to level seems to shift into only levelling on a round xthousand or xthousand-five-hundred, whereas the earlier levelling occurs on anywhere between an xhundred-and-fifty or round hundreds. Not sure if this peice of information helps or not, but looking at that I'm assuming there's no real precise formula. Maybe something general they used to decide a rough area of where level up should occur, and then rounded to the nearest five hundred. But it doesn't seem to be anything more...
    Then again, I'm not really great with math anyway. So I could be wrong.

  2. They could also use a formula and then round to the nearest multiple of 500 which would give a lot of false positives reverse engineering without knowing the exp for hundreds of levels.