Those were the days when the tower defence games genre on Android reigned supreme. If you're new to these parts, and to the tower defence genre in general, then a little explanation might be in order.
Tower defence - or TD as it is often abbreviated - takes some of real time strategy's frenetic live war-mongering, a little of turn based strategy's thoughtful unit placement, and condenses it into a format that's fit for mobile play.
There are various strains of TD, but in general they involve laying down automated defensive turrets ahead of incoming waves of enemy attacks. Get the placement and the mix of units right, and you'll form an impenetrable screen of death.
While we don't get as many tower defence games for Android as we used to, modern examples have started splicing in elements of other genres. Which means there's plenty of life in the old TD dog yet.
Kingdom Rush, along with its three follow-ups, is the pinnacle of tower defence. It's all thanks to a near-perfect combination of tight unit balance, intuitive controls, inventive and challenging level design, and a knock-out comic book aesthetic.
Bad North is a unique combination of real-time strategy and roguelike, but it's the distinct tower defence flavour we're interested in. Develop and position your troops to defend a series of besieged islands.
You might think of tower defence as an inherently limiting genre, applying a rigid framework to the strategy framework. But Dungeon Warfare 2 is a sprawling effort that has you constructing complete deadly dungeons.
If there's another series that has come to define mobile TD as much as Kingdom Rush, it's Fieldrunners. This second iteration takes the classic tower defence template and stretches it out as far as it can go in terms of variety, polish, and sheer volume of content.
You'd think we'd be tired of the Kingdom Rush formula by now, but we're not. This fourth slice of classic TD flips the script and places you in control of the original's big bad and his demonic forces. You could say that this one is true to the formula of the tower defence game for Android and other platforms!
'More of the same' is often a negative description. When it comes to the Kingdom Rush series, though, it's a ringing endorsement. A new setting, fresh towers, original heroes - same peerless TD gameplay.
Fieldrunners was superseded in pretty much every way by its sequel, but the original Fieldrunners is still one of the best TD games around. It's the original mobile TD hit, often copied, rarely bested.
Four Kingdom Rush games, all playing more or less the same - that's a bit much, isn't it? It would be, except for the fact that they all play so much better than almost all of their rivals. Meaning all four well deserved their spot among the best tower defence games on Android!
Tiny Defense 2, like its predecessor, flips the TD template around to a side-on perspective and makes everything look like a 16-bit mascot platformer. The result is one of the more welcoming TD games of recent times.
Like Royal Revolt, the Anomaly games turn TD on its head. Here you're in direct control of the attacking swarm that's running the gauntlet through your enemy's static defences. The resulting fireworks are spectacular.
Sentinel 4 took years to arrive after the influential Sentinel 3, and it feels suitably out of time. Packed full of systems and lacking much in the way of hand-holding, its old school TD approach is oddly refreshing.
Anomaly Defenders reverses the course of the earlier Anomaly games - which, as it turns out, brings it into sync with the other TD games on this list. It's a particularly pretty and nuanced example of the form, though.
An early example of the tower defence genre being chopped and spliced with other genres. CastleStorm has Angry Birds-like pinging, direct hack-and-slash action and more - and it all holds together very well indeed.
The Dead Island brand name is here put towards a surprising mixture of TD strategy and hack-and-slash combat. It's not the subtlest slice of strategy on this list, but defending a band of survivors from waves of the undead is sure to put a grim smile on your face.
Arknights casts you as a representative of a pharmaceutical company that fights both a deadly infection and the unrest it leaves in its wake. Add some sharp anime-style interstitial scenes, and you have a uniquely flavoured TD game.