The new Flappy Bird? Mr Jump hits five millions downloads in four days

There's a brand new iPhone craze in town, ready to fill the gap left by Flappy Bird — and it's called Mr Jump.

Clocking up an incredible five million downloads in just four days, Mr Jump has certainly made a name for itself - after passing the one million mark on its very first day.

Mr Jump is incredibly simple - there's only one button, which is 'jump', as your character moves left to right all by himself. When you come across an obstacle, tap your screen to avoid it - simple, right?

But like the greatest platformers from the 80s and 90s, the increased speed in later levels will test your memory for patterns and your reaction speed.

With only 12 levels built into the game - and more to come, the developers promise - that difficulty is part of the game's appeal. Like the addictive sensation that was Flappy Bird, seeing how far you can get before death is rewarding, as you (hopefully) get better and better.

Later levels add in extra obstacles and switches that must be jumped on, or turned on or off, with exact timing.

The game is free, supporting itself with occasional pop-up adverts (which can be removed forever by buying the game for €1.99). The next level is unlocked by beating the one before it - but the game does allow players to skip a level they're stuck on by purchasing a €0.99 "key" with an in-app purchase.

Technology news site Techcrunch reports that the app is already pulling in five figures a day in revenue for its three-man creative team.

The app is already the editor's choice in the iPhone app store, and with very positive reviews, looks like its success is only just beginning.