Despite launching to mixed review scores, the original Dead Island is Techland's greatest success story to date, with unit sales fast approaching the magical five million milestone.

But would the series have seen such success without that CGI trailer? And is publisher Deep Silver confident it can repeat its success with Riptide, now that gamers know exactly what to expect? talks to Deep Silver's creative director Guido Eickmeyer about the future of Dead Island, and what's in store for its sequel... sorry, spin-off Dead Island: Riptide. There's still an element of confusion over the game's canon, and whether Riptide should be considered a sequel or a spin-off to the original Dead Island. Why is Riptide considered a spin-off by Deep Silver, rather than a sequel, despite the fiction appearing to continue immediately after the original game?

Guido Eickmeyer, creative director, Deep Silver: It's the next instalment in the series and we wanted to develop something that builds on the success and feedback of the first game - delivering on our open world premise, but still bringing something new to the table. Doing a spin-off is the natural move. A sequel - as far as I am concerned - should be something really new, even rethinking fundamentals of the game, something that is more than continuing a successful path. We love games and we are still dedicated. The 'big guns' in this industry can rely on doing the same blockbusters again and again, but we need to be creative and innovative in our strategy.

Riptide introduces a fifth playable character, John Morgan. Did you ever consider adding five-player co-op?

GE: We considered it, like many ideas. In the first place, it sounds great and adds a new dimension to cooperative gameplay. However, we found that - within the current design principles - four-player coop is still the most enjoyable setup.

In the original Dead Island, enemies levelled up at the same pace as the player, something the game was criticised for in failing to make the player feel more powerful as the game progressed. Has this system been altered for the sequel?

GE: Slight adjustments are made, but we like the system. Is it better to ruin the player experience by simply overpowering him over time? Do we feel a zombie apocalypse turns into a cheesecake contest once you killed a bunch of the brain-dead? Truly not. Survival is our strongest motivation and a core element of the design. However, the skill system will ensure that you feel the improvement over time - and you will kick ass the more you advance, no doubt about that.

Did you anticipate the widespread success of the original Dead Island?

GE: To be honest, we did not anticipate this level of success. Close to five million units sold is beyond imagining for an independent game publisher. However, we should not take anything for granted from here on in and continue to develop the games we love to play. Our goal is to stick to what made us a winner in the first place.

After players got to grips with the final game, Dead Island's initial CGI trailer was deemed by some as being misleading. Is there a fear that Riptide's sales could struggle to match those of the original as a result?

GE: We did many gameplay trailers with in-game footage before the release, so labelling the CGI misleading would be ridiculous. We never pretended to be something different. In addition, Dead Island was the biggest and most intense cooperative multiplayer experience in 2011 and I believe playing with your friends or strangers next to each other through a horrifying zombie apocalypse is an emotional experience. I truly hope that at some point, even the last people in our industry will understand that games live by user stories, not pre-defined narratives. For watching a scripted experience, I still prefer a good movie.

Games similar to Dead Island, like Borderlands, saw tremendous success with DLC. What sort of attach rate did you see for Dead Island's DLC, and will there be a greater focus on post-release content for Riptide?

GE: We thought about it for quite some while. There will be DLC for Riptide, but we felt that a heavy dose of micro-downloads for a spin-off would feel like milking our target audience. We like the game, we like its scope, but multiple DLC packages would be over the top.

ZombiU brought back a sense of survival horror to zombie titles. What did you think of ZombiU?

GE: Very nice game. Surprisingly creative and fresh. To be honest, one of the very few reasons to buy a Wii U.

Did the title inspire Deep Silver to include or alter anything within Riptide?

GE: They are moving in a different direction. I believe we need to trust ourselves, find our own ways, not copying others.

Does Deep Silver hope to continue the Dead Island franchise long after Riptide? Is there any hope for a next-gen Dead Island game?

GE: Well, it would be surprising to shut down a franchise after such an outstanding success. What I can tell you at this point: There will be a lot of exciting news for our fans this year.

Techland is experimenting with a digital spin-off to its Call of Juarez series with The Gunslinger. Has Deep Silver ever considered something similar for Dead Island?

GE: Deep Silver will surely move in new directions with the franchise - and this may include digital only titles as well. We trust our team of designers and artists and I believe we will find concepts that combine innovation and quality in ways that people will like.

Dead Island: Riptide is scheduled for release on April 26 for Xbox 360, PS3 and PC.

Interview conducted via email