PopCap's Andrew Stein talks porting Plants vs. Zombies to iPhone

While all of PopCap's iPhone games have been massively successful, the one that everyone's been clamouring for since its PC and Mac release is Plants vs. Zombies.

Finally released, we caught up with Andrew Stein, PopCap's director of mobile business development, to find out some more about the process behind bringing it to the small portable screen.

Andrew Stein: Plants vs. Zombies engenders a lot of passion internally at PopCap and is one game the studio demanded be brought to iPhone.

In terms of final decision making, it certainly helps that it's won award after award and is the title our fans have been clamouring for as the next iPhone/iPod touch game.

Adapting the art and animation to the iPhone was a challenge because the screen is fairly small. For instance, the zombies give a lot of visual cues to their health state - traffic cones deteriorate as the zombie takes damage.

To compensate, we adjusted the art for all the zombies to make their heads bigger so that these cues were easier to see. It's not really noticeable unless you're looking for it but it makes a big difference in gameplay.

There's a huge amount of animation so we had to do a lot of optimisation and tuning so that the game could run in the memory footprint of the iPhone and run smoothly.

We also spent considerable time incorporating a new control scheme that took features of the device into account e.g. the fact that your fingers may be blocking important parts of the screen as you drag seeds to plant.

In my opinion, the most difficult thing to get right was the control scheme and animation. It's vitally important to Plants vs. Zombies' gameplay that you can place your plants precisely in the heat of battle.

Our creative guys tried a lot of different control schemes and I think nailed something that works really well. For me, I now feel the drag actually works better than the original PC/Mac version.

We used the same team that created Bejeweled 2 and Peggle for iPhone (and the original click-wheel iPod version in the case of Peggle). The work took roughly six months from start to submission.

We have added achievements to the iPhone game which weren't in the original. We also added a Quick Play Arena, which allows you to go back and replay any level once you've finished the adventure.

I think it is fair to say that Plants vs. Zombies is one of the most complex games that PopCap has ever made. The adaptation for the iPhone is tremendous. We hope you agree.

We haven't made any announcements about other platforms but I can say that PopCap loves to bring our titles to as many people as possible - and that means, as many platforms as possible.