A little gem from London-based studio Nitrome, Leap Day caught our attention not only with its simple and engaging jumping mechanic, but also its meta-format.

With each day comes a new level, which is only playable on that day (previous days' levels are locked).

The novel combination of one-level-per-day format plus the uncomplicated mechanics and rewarded video ad monetisation system prompted us to reach out to MD Matthew Annal to find out more.

PocketGamer.biz: What was the inspiration for Leap Day?

Matthew Annal: I think it was just an answer to the question most devs have. How do I increase retention?

We wondered if there was anything we could offer to get people to come back every day and considered new levels.

That seemed unfeasible at first but then we considered No Man's Sky which had been getting a lot of coverage in the press at the time and how is generated an entire universe from premade rules and assets.

Spelunky and Tiny Wings also became part of the discussion of a daily challenge.

How is each level generated - manually or procedurally?

It's a bit of both. We built lots (700-800) level chunks. Within that chunks can decorate to any one of 10 themes and enemies can be set to be multiple enemies which they often are.

We generate a number based off the date and use that with a bunch of rules we set to generate a unique level every day.

You call the game "A real labour of love from the whole Nitrome team". Can you explain a bit more?

It is the first game we have made where every member of the team got involved.

Mainly this was in building level chunks and play testing but also we had more programmers and artists working together than we usually have on a project.

We poured much more time than we budgeted for in the project and a lot of that was out of hours and just because we all really wanted to push the concept as far as we could.

Why do you think this daily update will be a strong enough pull for players to come back on a weekly, monthly, yearly basis?

We're hoping it will drive them back on a daily basis.

In our logic people stop playing a game because they run out of content (finish a game), get stuck, or because they feel they have done as well as they can.

In Leap Day if they get stuck they can always try again tomorrow and they can never finish it because there will always be a new level.

By putting an actual end to the level, we hope we stop users from maxing their enjoyment of the game in one sitting and eager to play the game again the next day.

Closing these drop off points left getting bored so we put a lot of effort into making the days seem as varied as possible.

Why did you decide to lock previous days' levels?

We didn't want to give free access to so many levels at once. The thought was that by pushing people to play one level and complete it that the draw to play the next day would be stronger and they would be less likely to give up.

Also, ideally we wanted people to be playing the same day at the same time so that it would generate conversation. Since launch a lot of people mention the same pain points on Twitter for example and that can spark more interest.

We considered not having levels prior to when the person downloaded it to reinforce playing the current day but ultimately we felt keeping people with the same content was important to people feeling part of the same thing.

More generally, the game could be seen a heavily-gated content wrapper for rewarded video ads. Do you think players will accept this?

We like to think that the game offers choice. It is more than possible to play the whole level without watching a rewarded video ad by skipping a few of the checkpoints and collecting as much fruit as you can.

In fact there are videos of people completing whole levels without using any checkpoints though that is a challenge. We also let people pay to remove ads entirely which makes checkpoints unlock for free.

So far the feedback for the checkpoints has been almost entirely positive.

What's the reaction been to the game so far in terms of downloads, retention etc?

We have had around 1 million downloads so far across iOS and Android.

We have yet to properly dive into the figures but revenue would suggest that something is definitely working and we assume it is retention.

Leap Day has been our best performing game to-date for week 1 and week 2 with regards to revenue.

We are obviously very happy with that and though we don't know what the longer term prospects are for the game we fully intend to update the game as much as we can to help retention even further.

If the concept is success, do you think you could use it in other games?

We would certainly consider using the concept again. We try to learn from each game and apply the lessons in future titles. It did however require a lot of man hours to make the concept work so I don't think we would risk it on every title.

Also we consider that users may become fatigued with the idea if we repeated it too much… plus there are many other things we would like to experiment with.