The shmup genre has long struggled to elegantly accommodate multiplayer gaming. At least, that's the case with 2D shooters that adopt or lean towards the pure arcade form. Shmups are designed primarily as solitary experiences, and to play them with leaderboard position in mind demands a great deal of nuance. There are scoring systems to milk, chains to maintain, and, of course, some very densely packed bullet patterns to negotiate.

Simply put, throwing an extra player into the mix often makes things a degree too hectic. The process of trying to dance in tandem with a given shmups's scoring system is quickly undermined if another player's firepower is ripping through fields of enemies you were trying to pick off one at the same time. Local co-op 2D shooter play can, of course, be fleeting fun, but typically there's too much going on to deploy scoring-minded gameplay strategies. And playing shmups for score is to really enjoy what they offer. There are exceptions, of course, but most of those exist in the indie shmup scene, where deviation from the arcade and credit-based structure can offer more flexibility, but potentially at the cost of genre purity.

Then there's the competitive arcade shooter, of which there have been very few, perhaps because they are so hard to design with any sophistication. ADK's beloved 1996 Neo Geo cute 'em up Twinkle Star Sprites is likely the most well known example, and then there's the more obscure 1999 release Change Air Blade, which deserves a great deal more attention than it gets. And now there is Rival Megagun, which absolutely follows in the tradition of Twinkle Star Sprites. Developer Spacewave Software has certainly done enough to distinguish its creation, but if you have played Twinkle Star Sprites, you'll feel immediately at home here.

Across the exclusively competitive Rival Megagun's various modes, the gameplay is anchored to a vertical split-screen set-up. Rival players occupy their side of the screen, where the same waves of enemies spawn in duplicate. Fundamentally things here are the same as found in a conventional shmup. There is a scrolling background, high difficulty, adversaries to blast from existence and swarms of gaudy bullets that do all they can to etch a mark on your retina.

Equally, the quick kill chaining system present in so many 2D shooters exists at the heart of Rival Megagun. Essentially, as you down enemies back-to-back, a combo multiplier climbs. Chain multiple kills together, and that combo meter soars higher and higher. If a few seconds pass without you shooting enemies from the sky – or, if you take a bullet – your combo multiplier drops back to zero. Meanwhile, concentrating fire on more persistent enemies serves to maintain the chain at its current level.

Traditionally a shmup chaining system multiplies the score you get for downing an enemy. Kill a foe with your combo multiplier at x10, for example, and you'll get ten-fold the base score given for destroying that opponent. In Rival Megagun, however, chaining does a great deal more than that. Primarily, every time you chain a kill, a small enemy drone will appear in your rival's screen area. That drone won't attack immediately. Instead, as your chain climbs, more drones will teleport across. Then, the moment you drop your chain, they will swarm the player or character you are competing against.

Killing enemies also fills an 'attack power meter', with chain level determining how much that bar fills. The attack meter can then be incrementally spent to fire special weapons into your competitors playing area. Depending on the character you use, you might scatter mines in front of your rival, or pester them with homing missiles. And if you max out your attack power meter, you can convert your ship into a gigantic boss form and swoop into your competitor's play area, pounding them with various bullet patterns. The ultimate aim, unsurprisingly, is to fell your competitor and win the round. Your ships can take two hits before being destroyed; in arcade mode, losing a round means sacrificing one life.

Arcade offers what is more accurately described as a campaign mode. That's because unlike typical arcade modes, in Rival Megagun things are festooned with storytelling and plenty of conversation. In short, Earth is at the mercy of an invading alien force known as the Harvesters, and through desperation, a televised contest is organised which welcomes any who dare to set off into space and try and repel the aggressive extraterrestrial forces. As such, arcade mode offers a series of rounds rather than traditional levels. It's actually structured a great deal more like an arcade beat 'em up than a shooter. Beating one opponent will push you to the next round, taking you deeper into a plot that exposes the truth of the competition.

Additionally, the rounds are available to be played individually via local multiplayer, alone against the computer, or as online PvP matches. Those modes are each perfect for the Switch set up as a portable, and in general, the game's short form offerings are ideal for handheld play. Tackling Rival Megagun's local co-op huddled around the Switch's tablet – kickstand out and controllers in hand – reminds you why this little piece of hardware is so special. Online versus is also great fun, simply because handing it to a real human – or having them belittle your flourishing shmup skills – is all the more meaningful an experience than having a scuffle with the (admittedly skilled) CPU components.

On the whole, Rival Megagun is a brilliantly fun shmup. Play is fast and tight, and there's a bounty of brilliant risk/reward gameplay moments to explore, as well as a good few ways to maximise score in arcade mode. Filling your rival's screen estate with drones, for example, will bother them plenty, but also give them lots of things to attack and therefore build up their chain, putting them in the perfect position to throw more stuff back at you.

Meanwhile, resisting depleting the attack power meter so you can transform into a boss means holding off and taking risks, but with a powerful payoff. Avoiding destroying smaller enemies too fast will mean the screen gets dangerously busy, but will allow you to claim a towering chain. And in general, extending the length of rounds will bring more opportunity to score, but increase the chance that you will be destroyed. All of that adds up to exciting, dramatic action where a bold, daring play-style is rewarded, encouraging you to push yourself and explore diverse strategies. And that is the making of a great shmup.

Visually the crisp, bold illustrated style is well-rounded and consistent, and the musical score offers an evocative, nuanced tribute to the greats from a time when you had to leave the house to play arcade games. Equally, the crunchy sound effects are excellent, bringing a seemingly tangible sense to the game's world.

That's not to say Rival Megagun is perfect. The bullet patterns are a little lacking in diversity, and too often too generic. And there is such an advantage – particularly in arcade mode – in focusing on converting into a boss form, that some of the other gameplay systems can feel almost surplus. Equally, while the strolling backdrops are very well realised, their design does little to bring to life a sense of place or atmosphere. They feel very much like backgrounds rather than places. Those critiques are pernickety ones, though. Rival Megagun is a distinct, exciting and considered shmup, and while it does dare to deviate from convention in a genre where compliance is celebrated, it remains authentic to the arcade form.

If you are a genre devotee, Spacewave's creation is fascinating and enthralling in equal measure. Meanwhile, if you're a curious newcomer to shmups, or have a more relaxed interest in arcade gameplay, it so perfectly fits the Switch form it really should be one you download.

Conclusion

Rival Megagun may fall short of the standards set by genre masterworks like Cave's Ketsui, Seibu Kaihatsu's Raiden Fighters Jet or Raizing's Battle Garegga. But those are some of the finest pieces of game design of all time, and failing to meet their lofty standards doesn't stop Spacewave's creation being a tremendously fun and rather distinct shmup that really does offer something fresh, and serves as a great demonstration of the Switch's multiplayer prowess in the process.