Adventure Time is ridiculously exuberant. Its characters are eccentric and weird, its storylines are convoluted and odd, and its humour is a mix of silly, low brow, and exceptionally well timed. It's a show of complexity and deep lore based on the insane. Adventure Time: Explore the Dungeon Because I DON'T KNOW! – as it's stylised for the only time in this review – is none of these things. It's instead a highly repetitive and shallow grind skinned in Adventure Time wears. And it's so very disappointing.

In the land of Ooo there are weird and wonderful creatures in the form of pretty much anything that you can imagine. Evil wizards and talking cat things, a unicorn-horse-dragon-rainbow, werewolves that want nothing more than to hug you, an entire kingdom of 'people' made of candy, and many other strange creatures make up the local population of this magical world. Princess Bubblegum – indeed, a princess made entirely out of pink bubblegum – has asked primary protagonists Finn the human and Jake the dog to venture deep into the depths of the royal dungeon full of bad guys to uncover the reason behind a bunch of recent breakouts.

It's a simple premise, but one that initially seems to fit the tone of the show. The royal dungeon has 100 levels, all of which Finn and up to three companions must explore to uncover the reason for the escapes. On your own as one of the four starting characters – the aforementioned Finn and Jake, as well as Marceline the vampire and a fourth protagonist that looks delicious – or with up to three friends in local multiplayer, you must descend the dungeon collecting treasure and battling foes. Eventually more candy characters are unlocked as you rescue them, including favourites from the show such as the Lumpy Space Princess. Each character has their strengths and weaknesses – some have more health while others can glide or otherwise manoeuvre themselves over deadly gaps and obstacles – but the tweaks are subtle enough so that choosing your favourite character doesn't put you at any disadvantage.

Unfortunately, the simple premise soon reveals itself to be just that: simple. The entrance to the royal dungeon acts as a hub for you to purchase items, switch characters, talk with bystanders, and accept additional side quests. You can then speak with Princess Bubblegum and you will be whisked away to the dungeon floor of your choosing – as long as you've unlocked it. Once down in the dungeon, every fifth level acts as a checkpoint and allows you to warp back to the hub overworld, meanwhile every tenth level pits you against a boss. If you die, you're sent back topside to trek through the dungeon again from the last checkpoint, although boss encounters give you a handful of tries before offering you a chance to continue with half your loot forfeited.

It's a strictly traditional dungeon crawler, and despite the colourful makeover, it's a soulless one at that. Levels are bland mazes with far too little treasure to make the adventuring profitable and far too few enemies to make them particularly challenging. Combat is basic, with a single button primary attack – which can be held down for a charged attack unique to your character – a single magical attack, a block, and a secondary weapon attack. Secondary weapons are strewn across the dungeon offering a mild variety of ranged and close quarters options to complement your primary approach. Unfortunately narrow hit detection can make squaring up on an enemy a bit awkward, so you'll often find yourself frantically searching for a secondary weapon you can swipe to broaden your attack.

Each time that you return to the hub, all of the treasure that you've found must be spent on that visit, as returning to the dungeon is met by a so-called 'Candy Tax' which strips your pockets clean. It's an effective way to ensure that you spend your earnings early, and it helps to encourage you to take more risks in the dungeon, going out of your way to collect treasure and choosing not to return to the hub at checkpoints. Sadly, it quickly leads to upgrades being way out of your price range and there's just not enough bundles of treasure to collect until much deeper in the dungeon. There are also tokens that you can nab, which can be equipped to characters in the hub overworld to augment their abilities, such as increasing your health, resisting status ailments, and preventing an attack from pushing you back. Character customisation doesn't get any more involved than that, unfortunately.

Adventure Time feels very old fashioned. The aforementioned basic combat, uninspired level design, and barebones narrative drains the source material of its charm and excitement, and the aesthetic doesn't do the rest of the package any favours either. While the locations are high-definition crisp, the characters, items, and enemies are pixel art versions of their cartoon selves. The juxtaposition of detailed backdrops to 16-bit characters provides the title with a nice nostalgic nod, but it completely strips the personalities of the smooth, bendy animation style that is such an important part of the show's identity. Fortunately, the 8-bit chip tune version of the show's opening theme is pretty good.