The idea of the first $10 billion mobile game first arose - at least in my mind - in the summer of 2015 during a talk from N3twork CEO Neil Young at the Develop conference in Brighton.
The first wave of $1 billion mobile games had just been announced - Puzzle & Dragons, Clash of Clans etc - so it was logical to discuss the next revenue milestone.
The main nub of that discussion revolved around whether the first $10 billion mobile game - what a lot of money that seemed at the time - would be a game already launched, or a future release.
As it happened both were true, sort of.
The first mobile game to reach $10 billion of lifetime revenue is Tencent's Honor of Kings, effectively a China-only mobile version of League of Legends.
Released in November 2015 - so technically at the time I was first thinking about it a future release - Honor of Kings was also released internationally as Arena of Valor in October 2016.
But this version has failed to gain much traction, at least in terms of revenue.
But not very far behind is Mixi's Monster Strike, a title released back in 2013, and like Honor of Kings, a game which only found success in its domestic market, in this case Japan.
Indeed, despite Mixi's best attempts, Monster Strike was launched internationally, backed with large scale marketing and totally failed. The international versions of the game were eventually pulled off the app stores.
In that context, the obvious conclusion to draw is that the most lucrative mobile games are those that dominate their home markets and manage to do so for years on end.
This isn't to say that games such as Clash of Clans, which are generally successful everywhere, won't ever hit $10 billion in lifetime revenue.
Released in 2012, it currently sits around the $8 billion mark, as is Puzzle & Dragons, which was also released in 2012 and like Monster Strike has only been successful in Japan.
Pokemon Go, Candy Crush Saga and PUBG Mobile (including its Chinese version Game for Peace) are fairly close behind.
But symbolic as the number seems, the prosaic truth is that given the size of the mobile games market - around $120 billion annually - a game that accumulates $10 billion in terms of lifetime revenue is actually much less interesting that it might at first appear.
Many mobile games can now generate over $1 billion a year so their roadmap to $10 billion is purely a case of doing the math.
Indeed, Honor of Kings and PUBG Mobile generated over $250 million in August 2021 alone.
Perhaps more significant now would be to ask, which will be the first mobile game to do $1 billion in a single month or $10 billion of revenue in a single year?
It's probably closer than you think.