There are a handful of Switch games we know we’ll likely never uninstall from our systems; an elite list of titles so addictive and so well suited to the portable nature of Nintendo’s system that they’ll always have a special place allocated on that MicroSD card. We’re talking about games like Mario Kart 8, Celeste, Axiom Verge, Into the Breach, Smash Bros. and, if you’re the kind of fancy type who’s upgraded their storage, Breath of the Wild. These are your long-haul flight friends, comrades on an epic car journey, the ones you turn to late at night for a wind-down session on the couch or tucked up in your bed – and Slay the Spire absolutely manages to join their ranks.

An extended period of Early Access on PC has seen Mega Crit Games’ beautifully balanced blend of roguelike dungeon crawler and deck-building card battler polished to perfection, receiving several important revisions that built on what was already a very solid base to reach the nigh-on perfect state in which we find it being delivered to Nintendo’s system. It’s an immediately irresistible formula; you choose one of three characters – Ironclad, Silent or Defect – each with their own special passive bonus, or relic and unique set of cards with which to gradually build your deck as you attempt to traverse three procedurally-generated floors worth of enemy encounters, chance events and boss battles in an effort to face off against the final nightmare atop the titular Spire.

The first thing that strikes you when you jump into your virgin run of Slay the Spire is how much information the game is willing to reveal to you with regards your enemy’s next move compared to your usual card-battler. The game’s 'Intent' system details every incoming attack, every buff or HP-sapping spell onscreen the turn before it occurs, maximising your engagement with the cards you’re dealt and enabling you to begin to formulate strategies from the get-go, immediately drawing you completely into the numbers and the nitty-gritty.

Knowing whether your enemy intends to attack, defend or buff itself, seeing exactly how much damage they’ll inflict or what status effect they’ll punish you with next creates an immediately addicting tension between playing defensive and offensive cards or, more importantly, creating a synergy between the two. It reinforces the importance of building a deck that’s flexible, that enables you to hit hard and stack attacks against an opponent or quickly flip to defence, shield-up to the max to absorb as much as you can of whatever onslaught is headed your way. Attack cards stack together beautifully here, enabling you to absolutely wallop your enemies with screen-shaking combos and wrestle every ounce of potential out of each hand you're dealt; this is what makes Slay the Spire so endlessly engaging. You’ll spend aeons sweating over which card to add to your deck, permanently unlock or upgrade next as you find your feet, every decision proving invaluable further down the line.

Jaw worms, Acid Slimes, Spheric Guardians and cultists, a host of Lovecraftian nightmares besiege you as you pick your way across the delightfully simple map; do you engage an enemy in battle to gain gold and add another all-important card to your deck? Do you try your luck at a chance encounter which may see you pray to some ancient god for a rare relic in exchange for a permanent chunk of your HP, outrun an Indiana Jones-style boulder attack or get dropped into a game-endingly difficult multi-enemy fight in some otherworldly coliseum? You can rest at bonfires, choosing to sleep and restore some HP or use the Smith there to strengthen your choice of one card from your deck; you may even get lucky and stumble across a treasure room full of rare and powerful relics.

Every decision you make on your way to the boss of each of the three floors proves to be vital in the fullness of time. Avoiding enemies will get you to your final destination quicker, but you’ll have a weaker deck, fewer relics and end up short on coin to buy helpful potions should you happen upon a merchant. A successful run at the Spire, once you’ve become worldly-wise and taken enough beatings to make one, doesn’t take all that long – which feeds into the addictive nature of everything that’s going on in the game.

The three different hero characters play impressively differently, and their completely unique set of cards mean a run with one will always be a unique experience when compared with another; they’re not just a new haircut and outfit. The Ironclad is the straightforward warrior, all heavy sword attacks and shielding, while The Silent is a rogue-type who's all about sneaky shivs and poison-coated blades. The Defect is perhaps the hardest to master, and is a sort of bionic mage; a curious mash-up of weapon and elemental attacks. These differing play-styles aren’t completely rigid, however; they’re malleable depending on how you set up your deck. Combine this with the seemingly endless supply of entertaining chance encounters and fantastical attacks and buffs spread across the three types and rarities of card on offer, and you’ll never make exactly the same run or pull off the same devastating combo twice, and, most importantly, never get sick of diving in for just one more pass.

After around twenty five hours’ worth of playing we’ve seen pretty much all of the enemies and chance encounters the game has to offer, and that does take some of the surprise out of things, but there's so much depth, so many layers and variations of cards, relics and different potions to fuse together on any given run that it seems churlish to complain that eventually, you’ll have faced every enemy. The PC version of the game may have mods to add new foes, but hey, we get to play this thing everywhere. Besides, we’re still new unlocking cards, finding new relics and finding ourselves completely enthralled every time we start out on a new run through the map. Alongside the main campaign there’s also a Daily Challenge mode that adds random modifiers to constantly change things up, as well as a custom mode where you can pimp a run to your exact specifications; also, let’s not forget the super-tough Ascension mode you’ll unlock with each character when you beat the final boss. All in all, we reckon there are hundreds of hours’ worth of entertainment here.

On the technical side of things, this Switch port runs beautifully in both docked and portable mode and the game’s big, bright and colourful cast of characters mean everything looks great and is easily discernible on the handheld screen. There are also no annoyances to report with text being too small; all the information on-screen is easy to parse and clearly laid out. We did encounter a handful of very slight framerate drops from time to time whilst we were shuffling quickly through our cards as a screen-shaking attack was going off, but they were few and far between.

Conclusion

Slay the Spire is an endlessly addictive roguelike card-battler that’s a perfect fit for the Switch; a beautifully balanced game that’s arrived on Nintendo’s system with all the benefits of an extended period of Early Access on PC. Its combination of ferocious battles, entertaining chance encounters and selection of three impressively different player characters make every run to the top a nerve-wracking and totally absorbing affair. Massively inventive sets of cards combine majestically into hugely destructive combos and attack and defense options fuse perfectly together, enabling players to use the information provided by the brilliantly transparent Intent system to strategize endlessly against the hordes of foul monstrosities that stand between themselves and victory. Sure, you’ll eventually see every enemy and chance encounter and yes, there are a few framerate niggles here and there, but overall this is one dungeon crawler that will live long in our system memories.