There has long been a question mark over the FPS genre on mobile.
In the early days of mobile gaming especially, the apparent incompatibility between the touchscreen interface and a satisfactory control scheme for shooters was oft-cited as a barrier to mobile establishing itself as a proper gaming platform.
And while that exposes the unprecedented extent to which the rise of mobile has broadened the definitions of gaming, there remain few compelling cases to suggest that mobile is a comfortable home for shooters.
Just as Gameloft's long-running Modern Combat series aped Call of Duty: Modern Warfare, mobile shooters still dance to the tune of their console and PC counterparts.
King, now Activision-owned, is working on a licensed Call of Duty game for mobile. And the genre's latest whirlwind success, PlayerUnknown's Battlegrounds, is already being imitated on mobile - with an official version to come.
But what are their prospects of finding major mobile success?
To explore this, it's worth exploring how some of the most successful mobile shooters out there are shaping up against the competition.
An exception to the rule that mobile shooters follow trends started on PC - though its colourful style owes something to that of Team Fortress 2 - is Guns of Boom.
Launched in May by Game Insight, this was a new FPS IP built around online, real-time PvP. In just over two months, Guns of Boom had racked up 10 million downloads.
It's currently the 22nd top grossing action game on iPhone in the US, making it the second highest ranked shooter. However, the relatively lowly position of the action category in the overall mobile pecking order means that this translates to 232nd in the US iPhone grossing charts overall, as of December 6th.
This paints a fairly accurate picture of Guns of Boom's grossing performance as a whole, the game peaking at 123rd and generally remaining somewhere between 150th and 250th in its life so far.
Outside the US, though, the game's done well in parts of Southeast Asia - peaking inside the top 10 iPhone grossing charts of Vietnam, Cambodia, Brunei and Laos - and in Europe.
These positions are solid enough, but it understandably raises concerns that a very modern mobile FPS can't break into the US top 100 grossing, despite the genre's enormous success on console and PC.
Another example of this would be Critical Ops, mobile's answer to Counter-Strike and a game that's certainly had no trouble getting downloads, having recently surpassed 30 million while still technically in soft launch.
But with an all-time peak of 371st in the US iPhone grossing charts and a ranking of 901st as of December 6th, the game certainly hasn't established itself among the mobile gaming elite just yet - despite the high number of downloads and eSports tournaments.
NetEase has initially launched its PUBG-inspired titles on mobile with no monetisation.
This might suggest that, when faithfully bringing gameplay styles more familiar to PC and console to mobile, it can be difficult to simultaneously introduce compelling reasons for players to engage with free-to-play economies at a mass market level.
Indeed, it's something NetEase clearly has no immediate answer to in the battle royale sub-genre - the firm has initially launched its PUBG-inspired titles on mobile with no monetisation whatsoever.
But of course, there's more than one way to bring the shooter to mobile. Indeed, the synchronous multiplayer offered by Critical Ops and Guns of Boom was not always technologically viable.
And above Guns of Boom in the US iPhone action games grossing charts - at 19th - is Sniper 3D: Shoot to Kill FPS.
Launched way back in November 2014 by Brazilian developer Fun Games For Free, it's not a game that's often talked about now. But it ranked at 164th in the US iPhone grosing charts as of December 6th and has dropped out of the top 300 only once in more than three years.
This is a far more traditional, single player-focused affair than the online multiplayer titles that are increasingly in vogue, but this shows the longevity that shooters can have on mobile.
Shooters can have great longevity on mobile.
Another example of this would be Gameloft's Modern Combat 5, also launched in 2014, which ranked 527th in the US iPhone grossing chart on December 6th.
Hunting a hit
Another long-running shooter series on mobile is Glu's Deer Hunter, whose consistent popularity made it the subject of a rather barbed reference in Sniper 3D's app description: "Hunting games? Boring. Start shooting real enemies, not deers, elephants, penguins, lions, or other any animal".
While Glu Mobile used to launch whole new entries in the series every year, Deer Hunter 2017 is actually just an updated version of the app originally released as Deer Hunter 2016.
This makes it another example of a mobile FPS with considerable longevity, the game ranking at 321st in the US iPhone grossing charts on December 6th - more than two years after the app's original launch.
This staying power suggests that there is a real appetite for mobile shooters and an audience that's willing to play and pay over a long period. However, it seems that the shooter's ceiling in terms of top grossing positions is considerably lower than that of other genres.
This theory will be tested when King applies its top-level monetisation chops to arguably the world's biggest FPS series in Call of Duty, and when Tencent brings serial record-breaker PlayerUnknown's Battlegrounds to the platform. There's also distinctly mobile IP getting new entires, including Madfinger's soft-launched free-to-play title Shadowgun Legends, which is looking to shake things up in the mobile shooter space.
But if even these cannot meaningfully change things, it's hard to imagine anything that will.