One of the biggest problems for an iOS gamer, whether playing on iPad, iPad mini, iPhone or iPod touch, is keeping up with the sheer volume. With the number of apps on the App Store closing in on a round million, it's utterly impossible for anyone to keep track of all the games being launched each week - forget catching up on the classics that were launched two, three, four or more years ago. (At least iOS gaming only has five years of history - it could be worse, we suppose.)

To help iPad and iPhone gamers keep track of the really unmissable titles out there, here are six of the most essential iOS games. Some have been out for ages (comparatively). You may have played some already. But if there are any here you've not tried, it's time to get down the App Store.

To read expert reviews of the latest iPad and iPhone games (as well as classics like these) check out our iOS reviews section.

Want more? Try these: The 60 best iOS games ever: Great gaming apps for iPad & iPhone

How to record iPad gameplay videos

1. Angry Birds series

Company: Rovio
Requirements: iPhone, iPod touch and iPad
Price: from 69p

There are so many games available for iOS devices now that it’s impossible for us to do more than just skim the surface. However, there’s no doubt that Angry Birds still rules the roost with more than 500 million downloads to date. The original game is regularly updated with new levels, and spin-offs such as Angry Birds Rio and Angry Birds Seasons keep the fun going.

The puzzles – in which you use an assortment of exploding birds to attack pigs holed up inside various buildings – continue to tease and infuriate, and seem to appeal to both young and old.

Angry Birds Star Wars review

2. Real Racing 2

Company: Firemint
Requirements: iPhone, iPod touch and iPad
Price: £2.99; £4.99

Real Racing 2 is a cracking single-player racing game, with excellent, detailed 3D graphics, responsive driving controls and a variety of playing modes. There’s an extended Career mode that takes you through a series of events, as well as a Time Trial speed-test mode and a simple Quick Race mode where you can practice your skills. However, it’s also one of the first games to take advantage of the new online features in iOS 5, which allow you to play with four people on a WiFi network and to display the game on an HD TV via an Apple TV.

3. Dungeon Hunter 2

Company: Gameloft
Requirements: iPhone, iPod touch and iPad
Price: £4.99

There are quite a few roleplaying games for the iPhone and iPad, but it’s the Dungeon Hunter series that best captures the addictive combat-and-looting formula of the old Diablo games on the Mac. The storyline is pretty feeble – you’re a prince who goes to war in order to save your kingdom from monsters and stuff. However, the slick graphics are as good as we’ve seen on many Mac games, and this sequel has am enjoyable multiplayer mode that lets you play with up to three friends using either a WiFi or Bluetooth connection.

4. Modern Combat 3: Fallen Nation

Company: Gameloft
Requirements: iPhone 3GS, or later, iPod touch third gen, iPad
Price: £4.99

Modern Combat is the closest we’ve seen to the realistic combat of the Call Of Duty games for the Mac and PC. The 3D graphics are slick and finely detailed, and the action just never lets up. The main single-player games includes 13 missions in which you protect the US. Locations range from Los Angeles to Pakistan with different types of mission, such as escort duty, helicopter action, and seek and destroy. There’s also an online mode for up to 12 players.

5. NOVA 2

Company: Gameloft 
Requirements: iPhone, iPod touch, iPad
Price: £4.99

If Modern Combat is the iPhone’s answer to Call Of Duty, then the sci-fi-oriented Nova 2 is our version of Halo. The single-player campaign consists of 12 missions sets on a series of space stations, in which human forces fight against the Volterites. These mysterious enemies bounce around with jetpacks, so you need to be fast and accurate to keep up with the high-speed action. However, you’ve got your own impressive armoury to help out, including weapons such as the lightning gun, frag grenades and dual hand guns.

6. Cut The Rope series

Company: Chillingo
Requirements: iPhone, iPod touch, iPad
Price: 69p; £1.49

Like many of the best puzzle games, Cut The Rope is based on a very simple idea – you just need to cut a series of ropes in order to drop bits of candy down to the a cute little character called Om Nom. However, that simple task leads to some mind-bendingly complex puzzles, as you work your way through more than 200 different levels. It gets harder as you go along too, with additional obstacles, such as jagged spikes and electrical fields, adding to the fun.