"It's not a bug, it's a feature." This is a phrase that's often thrown around in a lighthearted manner, but there's some truth behind the words. Programming errors can often lead to fascinating results that were never intended, creating a sense of excitement when one stumbles across a curious glitch that's obviously not supposed to happen. Evidently, Tom Happ really appreciated this phenomenon, as he constructed Axiom Verge to heavily revolve around bugs and glitches. Through this, Axiom Verge stands as one of the most memorable and inventive 'Metroidvania' games in years.

The story begins with our hero, Trace, finishing the final preparations for an experiment in his lab. The experiment starts out well enough, but things quickly go awry and the lab explodes, evidently killing Trace and his colleagues. He then wakes up in a strange egg-like machine in a grim world, guided by a disembodied voice. Is Trace dead, or was he teleported to another world? What's real, what's illusion? Axiom Verge excels at keeping the player guessing; you're never given all the answers right away. The endless mystery provides a great motivation to keep playing, even beyond the fantastic gameplay.

Axiom Verge plays a lot like a faster and punchier Super Metroid. There are no floaty jumps here, everything is quick and responsive, which naturally means that firefights are filled with more fast-paced action. You're given a standard peashooter to begin with, but the arsenal quickly fills out with a diverse array of colourful weaponry that suit every task. No two weapons behave exactly the same, and the variety on offer lends a nice layer of strategy to proceedings. Do you charge in with a shotgun style weapon and finish off a horde of enemies quick and dirty, or do you stay at a safe distance and pick them off with a more technical weapon? The choice is yours, and just when you're getting tired of weapons you seem to find another one. These weapons are upgradeable, too; attributes such as range, damage, and projectile size can be upgraded by finding collectibles along the way.

Of course, the major feature of Axiom Verge is the emphasis on glitches, and it's handled in a wonderful way. Early on, you're given a "glitch gun" that allows you to stabilize or destabilize certain objects. Douse a suspicious wall with it, and it may give way to a secret room. Blast enemies with it and they may become easier or harder to beat. You never know what will happen, and it's always a thrill to see what it can do. Also, there are randomly located "glitch worlds" that can appear virtually anywhere. There's no rhyme or reason to these, but they're almost always worth investigating. The maps are laid out in a haphazard, meandering fashion, the room designs make no sense, and enemies spawn erratically, but these glitch worlds can net you upgrades and collectibles that you otherwise wouldn't have access to.

Bosses are a huge highlight of the experience, too, with inventive and memorable fights showing up every once in a while. There's generally a fantastic sense of scope to them, as the camera pans out quite a bit to fit the whole boss onto the screen and you see how small Trace is in comparison. While none of the fights are that challenging - especially if you thoroughly scour every nook and cranny for upgrades - they do a great job of breaking up the flow of gameplay and often lead to yet another area or significant upgrade being made available.

The graphics are some of the most detailed that we've seen for a retro-inspired game such as this, with some remarkable attention to detail on constant display. Sprites and backgrounds are quite complex, with the bosses offering up some particularly nice eye candy. Though the colour schemes in different areas can tend to be somewhat monochromatic, it usually suits the mood well and helps add to the atmosphere. Axiom Verge excels at creating a legitimately creepy environment that oftentimes has more in common with Dead Space than Metroid, and this darker style can lead to some tense sequences. Standout moments can be found when exploring the mysterious glitch worlds, when the hue of the screen takes on a sickly colour, tiles and sprites regularly stutter, and the whole thing looks like it's being viewed on an old CRT.

The soundtrack is on par as well, offering a distinct and unsettling score that matches the pace of the gameplay well. As is expected, most tracks typically take on a dark, sci-fi sound, but this is a solid mix that occasionally may surprise you. Axiom Verge's soundtrack sets itself apart by how weird it often sounds, it's full of memorable, nightmare-inducing tracks such as this. Oftentimes you may find yourself caught off guard by the bizarre music upon entering a new area, something which makes the exploration all the more exciting.

Of course, we'd be remiss to not mention the Wii U exclusive features. As is standard by now, the GamePad helps a lot by streamlining the experience, as opposed to adding gimmicks to it. The GamePad screen adds extra features such as an interactive map and selectable icons for all your guns, along with Off-TV Play. It's nothing mind blowing, but these features help to make the overall experience more convenient. Also, for speedrunners, there are leaderboards for posting your best times; that's sure to be very attractive to dedicated players.

Conclusion

Axiom Verge is an excellent Metroidvania, one that Wii U owners should absolutely not miss out on. Creative gameplay, beautiful visuals, and a compelling story all blend to create a fantastic game that does a great job of paying tribute to classics while doing something wholly new with the established formula. It's made all the more impressive, too, by the fact that the entire thing is the product of one man's dedication. If you have the remotest interest in 2D action games, do yourself a favour and pick this game up.