Still digging through old magazines and Retro Gamer keeps serving up interesting features.

Published in 2014 in Retro Gamer Annual Volume 1, the list contains "some of the most brutal games ever made."

With shoot-'em-ups being extra challenging, you'd expect a few on the list.

Which shmups made the cut?

Defender (Difficulty 9) is referred to as "insanely difficult."

Ikaruga shows up twice in the list, the first time to note how the difficulty spikes throughout the game.

Queen Larsa from Mushihimesama Futari is listed in the Hardest Bosses category.

There is special "Bullet Hell" subsection!

ROBOTRON: 2084 (DIFFICULTY: 8)

Robotron is the second Eugene Jarvis shoot-em-up to make our feature, and it’s not hard to understand why. It distils the genre into its purest form and remains one of the finest

and toughest

twitch shooters of all time. Everything about Robotron is beautifully balanced, introducing a steady stream of suitably different enemies that require both skill and knowledge to defeat.

There are no power-ups, no special abilities

it’s just you, those two intimidating joysticks and a seemingly never ending supply of enemies to deal with. You'll get a brief couple of seconds at the start of each round to get your bearings, but you’re then thrown into a chaotic war zone that will test your skills to their limits. Add in the brilliant risk/reward system in the form of stragglers who can be saved for cumulative points, and Robotron remains one of those rare games

a tough experience that always drags you back for one more go.

I haven't played this one, but it can be played in browser. It looks like fun.

SLAP FIGHT (DIFFICULTY:9)

Toaplan certainly knows how to make tough shooters. Slap Fight is mainly memorable because of its insane ultimate power-up that turns your tiny fighter into an insane armada of death. Most mortals never get to experience the sheer power it offers, as they'll never survive long enough to witness it.

Slap Fight is insanely hard for a multitude of reasons. The enemies are frequent and painfully accurate, while ships will constantly sneak up and snipe you whenever possible. It’s the lack of reach that really makes Slap Fight tough though. Your base bullets only hit halfway up the screen meaning you're constantly dicing with death whenever you try to take down enemies. A truly tough challenge.

I'm really glad this is listed here. I have read in more than one place (and heard it mentioned on podcasts and YouTube videos) that this is an easy game. It requires so much memorization and placement to get through to the end. I haven't even seen the 3rd boss I think!

HELL FIRE (DIFFICULTY 9)

Toaplan’s shooter is aptly named, as it’s an absolute bitch to play. The real beauty of Hell Fire lies in its clever game mechanics, which evolve around a cleverly designed firing system. Your ship can fire forwards, behind, diagonally and up and down, giving you a tremendous amount of reach. The trick here of course is that you can only fire in one of the directions at a time, which turns Toaplan’s game into a deadly juggling act where you desperately try to fend off waves of sneaky enemies that attack you from all sides. The Mega Drive version makes things slightly easier by equipping your ship with an additional power-up that spews fourth a deadly plasma bolt, but ultimately it remains an extremely punishing shooter that separates the men from the boys.

This is a favourite. I'm awful at it, but it doesn't matter. That first track puts me in a good mood.

VIEWPOINT (DIFFICULTY 10)

When we were asking readers about tough shooters, Viewpoint came up again and again. First released in arcades in 1992, it's notable for being isometric, featuring rendered visuals and for being bloody hard. Simply surviving the first level for many will be an achievement in itself.

One of the more interesting aspects of Sammy's shooter is that the environments are just as dangerous as the enemies and bosses. You'll often find yourself dodging fast-moving barriers or shooting gates in order to disable them as you battle across Viewpoint's varied stages, and it becomes a reflex test as you weave through bullets, hazards and enemies.

Also playable online, this one looks like great fun.

IKARUGA (DIFFICULTY 9)

Ikaruga is a tough game at the best of times, but it becomes almost impossible if you try playing it properly. Like many classic shoot-’em-ups, Ikaruga not only features great game mechanics, but also a highly polished scoring system. Polarity is the big thing about Treasure’s spiritual successor to Radiant Silvergun and it’s beautifully presented here.

The developer had already experimented with the concept of flipping between different polarities in Silhouette Mirage, but it’s far more intelligently presented in Ikaruga. Your ship is black on one side and white on the other. The white portion of your ship can absorb white bullets but will get instantly destroyed by black ones, while the reverse is true for its black underside. The kicker here though is that enemies are destroyed more quickly by their reverse colours and that you need to shoot three enemies of the same colour to increase your multiplier. As a result you’re continually switching sides, doing everything you can to keep your multiplier up, while avoiding an endless barrage of bullets. Brutal, but oh so brilliant.

This is the game I've been waiting to play for ages. I think I'll just buy it digitally because I doubt I'll ever find a physical copy for a reasonable price.