Dungeon of the Endless opens on a shot of a spacecraft crashing deep into the surface of an unknown planet and hopes that you will work out details like the plot and what on earth you're supposed to be doing, from there. Featuring procedurally-generated dungeon exploring, with hints of RPG and tower defence, this is a challenging journey into the unknown which has a lot to offer beneath its simple exterior.

With two starting difficulties of "Easy" and "Too Easy," you'd be forgiven for assuming that Dungeon of the Endless is either going to be a walk in the park or a nightmarish slog. It's certainly challenging, but manages to be engaging enough to encourage you to persevere against ever-mounting odds. It isn't all that forthcoming with its story, or even in guiding the player in what their objective might be, so there's a lot riding on gameplay to keep players engaged.

We did eventually find a tutorial in the options menu and would highly recommend you seek this out before you start, as it really isn't clear what's going on or why. The "Help" screen is also very good. You are asked to pick two characters to control and select a difficulty level, before starting in the wreckage of your downed pod, with a closed door in front of you and a large crystal in the room. Eventually, you will discover that the spacecraft was a prison transport and that your job is to get the power crystal from the pod back to the surface of the planet by finding the elevator on each floor.

It's a game of exploration, then. One that demands that you learn by experience and improve on each playthrough and one that doesn't give up its motivations so easily, choosing instead to tell its story gradually as you unlock photos in an album and catch commentary from the prisoners and guards as they make their way through the dungeon. There's a constant need to see what's behind the next door - it could lead to escape or it could unleash a horde of monsters. Perhaps you'll discover a new technology that will help you on your journey or you'll meet a new survivor to join your team? There's only one way to find out.

There's also the matter of resource management. As well as keeping your survivors alive, you will need to gather and wisely distribute the resources you gain each turn. Industry will allow you to build generators, turrets and other useful items, science allows you to discover new structures, food is used to heal and level up your characters and finally, there's the all-important Dust. Dust is what makes your power crystal work and is used to power the rooms in which you build your structures. Every time your crystal is attacked, you lose dust, meaning you can power less rooms in the dungeon. Rooms without power do not generate resources, their turrets don't function and most troubling of all, they have a chance to generate a wave of monsters every time a new turn starts. It's unlikely you'll have enough dust to power the entire dungeon, so it is wise to build safe passages to your destination, rerouting power as needed to minimise the potential of an enemy swarm.

Dungeon of the Endless is turn based, but turns are not limited by time. In fact, during each turn you can walk around any room you have already explored, level up, build structures, or mess around with your kit. The turn starts when you open the next door, revealing new areas, spawning monsters or opening up new characters to unlock. Each character has their individual strengths and weaknesses which will help you to achieve your objectives and they can be equipped with items found throughout the dungeon or bought from merchants. Characters can level up - gaining new skills, higher HP and other stat boosts which will aid them in their journey. As you'll be expecting the survivors to fight off waves of enemies using whatever weapons and skills you've given them, it's vital to ensure they are up to the challenge - especially as they will move at a fraction of their normal speed when transporting the power crystal, making them ever more vulnerable.

There are 12 levels between you and the surface and each play through will be entirely different, based not only on your starting characters, but also the configuration of your dungeon, which structures you build, how you spend your resources and whether or not seven waves of enemies spawned just as you were about to reach the elevator and reach sweet, sweet freedom. There are 18 characters which can be unlocked by recruiting them in the dungeon and keeping them alive for three floors (or by completing the game). Meeting certain win conditions also unlocks different escape pods which add a whole new set of conditions to your dungeon run.

Visually, the art style is decidedly retro. The backgrounds and character image art work well enough, but the sprites themselves are not always as successful. It can occasionally be difficult to work out what is happening on screen when there are more than a couple of enemies in the room (so, most of the time). The sound is stylised to fit in with the retro theme and does so very well, never intruding on the gameplay experience, but augmenting it expertly. When between floors, the music takes on an elevator muzak tone which is sure to draw a smile when accompanied by the survivors telling stories in their brief moments of respite between stages.

Interestingly, Dungeon of the Endless has a multiplayer option where, instead of creating a band of four characters that is controlled by you, instead you can team up with three others over Xbox Live and control one character each. Resources are not shared in multiplayer so communication is a must in the later stages to ensure that these are being used to the maximum benefit of everyone in the game. Unfortunately, it can be a real struggle to find a public multiplayer game on Xbox One at the moment, so we'd recommend jumping in with a couple of friends if you can.

Conclusion

Full disclosure, in the ten hours we spent with Dungeon of the Endless over the course of this review, we didn't escape from the dungeons. Even playing on the inappropriately named 'Too Easy' mode, this rogue-like can turn on you in an instant. Take your eye off the ball and your previously flourishing band of survivors can be unceremoniously wiped out, taken down by rapidly spawning hordes of enemies without so much as a last breath with which to cry for help. But it's a game that, once it has you hooked, will reel you back in over and over again because you just know you can do better this time, or perhaps you think you've discovered a new strategy - it's all very compelling.