It's been confirmed today that Mario Kart is now the best-selling racing franchise in the US, with the latest entry - Mario Kart 8 Deluxe - selling just under 1,000,000 units in its first month on the shelves.

Now in its 25th year, the Mario Kart franchise has managed to remain an important and well-loved mainstay and maintained its core values without giving into the changing tastes of the average player. In fact, that's just one of many reasons why it's still so popular after a quarter-century.

What Mario Kart has always gotten right and never lost sight of is fun. From the beginning - 1992's Super Mario Kart for the SNES and Super Famicom - it was all about honest, no-frills fun. There was no steep learning curve with it, no need for endless customisation and a simple interface that allowed for every player of every stripe to enjoy. It might dismissed as lacking depth or nuance, but really, it's about the simplest and most direct version of a racer.

You strap in, drive as fast as you can and as skilfully as you can, and hit the finish line first. That's it. There's no balancing the wheels, no drafting or other superfluous physics to it, no changing the drive-shaft or using slick tires for a particular track or circuit. Sure, the different characters have different strengths, but they're balanced well. Each player plays to their own character. Princess Peach is lighter, but can take corners faster. Bowser's an armoured tank with incredible grip. Mario's an all-round, entry-level choice. It all just works.

More than anything, Mario Kart - through all its different iterations - never tried to be anything other than what it was. When you look at the fallen franchises of the same generation - Castlevania, Sonic the Hedgehog, Tomb Raider (although that's enjoying a second life at the minute) - they tried to add more and more in an attempt to keep players interested, instead of refining what got people playing in the first place.

You can just as easily pick up play Super Mario Kart or Mario Kart 64 as you can Mario Kart Deluxe 8 and, within a few short minutes, you're off and racing. The DNA hasn't been changed in twenty-five years because it never needed it. Sure, when you compare it to other racing franchises like Gran Turismo or Forza, Mario Kart comes up lacking in terms of realism and depth. But there lies the key difference between them - Gran Turismo and Forza are racing simulators, designed for petrolheads who want to get as close as they possibly can to the experience of driving a supercar. Mario Kart is about pure speed and driving.

The designers may not have been attempting to create the best racing franchise of our time in 1992, but they understood that simplicity of design and intent was the easiest way to a fun experience for players.

Twenty-five years on, that's pretty much all you look for in a racing game.