While freemium has been the one of the defining trends of iPhone gaming in 2010, it's taken a long time to rise to prominence.

Indeed, while the likes of Zynga, Playdom and ngmoco spent time streamlining their processes for the platform, it's been indie startups such as The PlayForge who have arguably made as much impact.

Set up by Vince McDonnell in his living room, the release of Zombie Farm in February demonstrated that if you're nimble enough to catch the right wave, you can gain a huge audience and launch a very successful business.

PocketGamer: Why did you decide to get involved in iOS game development?

Vince McDonnell: Around July 2009, I started thinking about it while at my old job, developing console games for movie titles.

The console industry is brutal and the overtime is intense. Seeing veterans get burned out only to be replaced with eager new grads who await the same fate was rough. I was looking for a way out when I read an article about a person called Steve Demeter who made a fortune making iPhone games.

Then there was another article about a neat game called iShoot that made a lot of money as well.

All these articles kept talking about this as a Gold Rush. Whether this was propaganda or not, I was so sick of my job that I didn't care. Heck, I didn't even own an iPhone or iPod but was so committed to doing this that I bought my first Mac and started learning Objective C to begin development on the iOS platform.

You had a couple of releases before Zombie Farm, so what did you learn from them?

Chore Hero was my first iOS title. It didn't take me too long to create and was pretty well received. Still, it didn't make any money at all. After I put out a second and third productivity app, those didn't fair much better.

But what I did learn from those experiences is that one person can make great apps. So, I took what I learned and decided to stick to what I knew; games, which would be my final straw.

My wife was working two jobs at the time, and even then we were going broke because of a mortgage. So I started dedicating every waking moment to making this game happen.

What was the inspiration for Zombie Farm?

Having less free time, I started playing casual games and was a big fan of FarmVille. However, I was disappointed that I couldn't play it on the go. I also thoroughly enjoyed the playful, charming ridiculousness of Plants vs. Zombies.

I thought how cool it would be if I could mix my favorite games together. Why not plant the zombies and the veggies and watch them both pop out of the ground together?

How did you try to make it appeal to the FarmVille audience but also to be distinctive?

When I first came up with the idea for Zombie Farm, I wanted to create something that was family friendly, harvesting oriented, and socially capable, similar in a few ways to the FarmVille-type games. That way when people see the game, they are greeted with a familiar interface that doesn't require much learning.

Zombie Farm has a slew of differentiating factors though. At its core, it's two games in one, with the fighting/combat elements in tandem with the farming mechanic.

A hurdle I had to cross was how to make zombies, naturally morbid characters, family friendly. Personally, the idea that originally got me excited was the goofy zombies who think about butterflies and rainbows, that you plant and grow and who will, in the end, help you out. It essentially turns the traditional zombie archetype on its head.

As the game has evolved, I've also added features like zombie abilities, and mutations that let you make bizarre vegetable-zombie creations. It's pretty fun to see what combinations you can come up with.

When did it become clear to you that Zombie Farm was going to be a success?

After launch, the very next day it grossed $500. My wife and I started jumping around and dancing with excitement! "Hard times are done, we won!" Then the day after that it made $2,000, and $4,000 the day after. Every day it doubled.

As if that wasn't enough, Apple featured the game in its top carousel and a week later it was the #4 top grossing game. We've continued to stay close to the top of the iTunes charts and we've received more than six and a half million downloads to-date.

Also, the community has been extremely active on our Facebook page which I always feel is a great indicator of continued success. The feedback and insights from them have been invaluable and we are really grateful for that.

How have you gone about supporting and updating the game?

We're consistent with our frequent iterations of Zombie Farm, adding mutations, items, crops and doing special updates on a monthly basis. We've recently added day and night elements to the farm. It is reflective of the player's actual local time. We've also added Game Center along with enhancements to online play.

We are just consistently adding engaging elements to the game. Much of our update content is inspired by fan feedback. We listen to the comments from players and make adjustments accordingly. We want to give our players the most fun and engaging experience possible.

As a casual game that's not built on Facebook, how have you ensured its community features work well?

Web/network programming is not my strong suit, so I used the Facebook Connect SDK for this. Facebook Connect in conjunction with Playhaven have helped me achieve community features that I couldn't have created myself.

Zombie Farm has only recently been implementing online features like cloud-saving and player-to-player gifting.

We like to build in fun incentives for players to join the community too. It gives them a vested interest in the game and future updates. We even have a neat feature not many people know about - players might notice that some of the zombies in the game are named after their own Facebook friends.

What plans do to you have to bring Zombie Farm to other platforms?

The Android Market has been rapidly expanding so we definitely want to consider adding the game to that platform. I think it's a common sentiment among developers that Android is looking more and more viable.

We have played around with the concept of building a version for Facebook. Nothing is out of the question. We want to bring the game to as many players as possible.

Do you think freemium is the best business model for mobile games?

This model has worked well for us. Zombie Farm can be played all the way through without making any in-app purchases which is great because it brings people to the game.

I have come to believe that you should not require players to make purchases at any point in a game. Some players choose to purchase virtual goods but they commonly just do it to boost progression or in some cases yield cooler items.

The brains (our in-app currency) in Zombie Farm enhance the gaming experience; they are not mandatory for progression. That's something we are pretty adamant about keeping.

What's next for The PlayForge?

More games for the iPhone/iPod of course! The iTunes App Store has been a great medium for indie developers like us. It has really simplified the distribution process, which is great. We are exploring new platforms though.

We have a few things in the works right now and hope to make those announcements early next year. Stay tuned. The Playforge has a lot of big plans for the future and we are sure to keep our players in the loop.

Thanks to Vince for his time.