Last week, Finnish developer Supercell held its Free Your Play 2013 festival.

Tomotaka Motoyoshi and Daisuke Yamamoto from Puzzle & Dragons developer GungHo Online were two of the special guests.

After all, the two companies have just launched a cross-promotional push between their games that's seen Clash of Clans rise to the top of the Japanese free iOS chart.

And we grabbed the two for a quick chat.

They explained how the original version of Puzzle & Dragons was developed by only four people, although that's since increased to 20.

Still, producer Daisuke Yamamoto hopes it's going to rise some more soon - he says he working really hard.

You can check out the full interview below, or check out our complete listing of Free Your play video interviews here.