It’s 6am, and tempers are fraying. We’ve had a long night, but the eighth (and perhaps finest) level of the Halo 3 co-op campaign – The Covenant – has our four-man party clamouring to recall stories of Silent Cartographer, the crowning glory of Halo: CE.

It’s a sharp reminder of a long-forgotten gameplay rush, a level beloved for green rolling hills and the most prominent of free-form AI hooks on which Bungie hangs its celebrated set pieces. This was the simultaneously nostalgic and progressive experience we were all seeking. This, we declared to one another, was what console shooters were all about.

Once more unto the beach, dear friends.

And yet suddenly, without warning, the colour palette fades from a brazen mix of green and purple to a squidgy, tepid brown as we enter the penultimate fight. The following procession of colonic tunnels—bridged by alluringly shiny sphincters—pitch us into a series of tough, repetitious battles against the moronic Flood, punctuated by a slow-motion narrative exchange between a giant talking plant and a fictional AI. In a moment of sly self-reflexivity, Master Chief surveys this rotten quagmire from afar, inspecting the muck dripping from the bottom of his boot apologetically.

Welcome to the nadir of Halo design. Welcome to Cortana.

It’s a level that should never have been. Taken on its own, it’s a crime against an otherwise solidly-designed FPS, perfectly positioned to ruin the conclusion for a sizeable chunk of the player base. Taken in the context of the series—and specifically the horrifically misjudged Library from CE— it’s a chink in the design principles of an otherwise celebrated developer. Whether attributable to complacency or no, this misstep precluded Halo 3 reaching classic status amongst many critics and fans – all for what basically amounts to a brown smear.

Definitely not Kansas.

Of course, to chastise a shooter simply for attempting something different within the genre’s narrow confines would be churlish. Diverting enemies from human-like AI to zombified path-finding can make for a welcome respite in any given shooter (triggering security bots in Bioshock a prime example). The odd corridor section, shooting gallery or on-rails sequence is akin to a palette cleanser.

Hell, the likes of F.E.A.R can even exist solely on such limited sustenance; though many would argue that entire game to be a badly designed single player level, no matter how impressively its soldiers hide behind corners.

But there is something about a comprehensive change of location—coupled with style and enemy type—that ensures it rarely meets with success. From Gordon Freeman’s entirely unnecessary sojourn on Xen through to the frosty corridor-based conclusion of Crysis, this seems a design problem consumers are destined to relive. But bad levels are not always the result of a change in setting, and some are even difficult to identify at first glance.

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