Credit where it's due: it's a fine idea. A cheerfully camp multiplayer FPS starring teams of Batman and Joker impersonators on a budget, with Call Of Duty's rank-and-unlock system and an extensive layer of character customisation that not only affords variety and individuality but also opens the door for publisher-sating microtransactions. Batman pools his wonderful toys with the Joker's, with nods to the Arkham series – boomerangs, gliders and dive kicks – and comic book reimaginings of multiplayer FPS standards like claymores, here replaced with booby trapped jack-in-the-boxes. Rollerskates and double-jump boots affect movement on the ground, while the likes of the glider and grapple hook afford aerial mobility.
The game is chaotic and enjoyable at first – once you get into one, anyway, as its matchmaking is so terrible it barely deserves the name. You'll sit endlessly in lobbies waiting for players that will never arrive, and there's no way to join in-progress matches, so if someone on your team quits mid-game, you're a man down for the duration. While the core mechanics are robust enough, the only confirmation that you're shooting straight comes from the numerical damage values that appear on enemies as bullets connect. Turn them off in the options screen and opponents move around with no indication their skin is being pierced by searing metal – until they fall over.
Avatars are fully customisable; while costumes are purely cosmetic, body types have a genuine impact on play. Small characters are quicker and harder to hit, while the larger ones have more health and aren't slowed down by heavy weaponry. There are mascots, which follow you round the maps, and calling cards, a take on Black Ops' Playercards. Some are unlocked as you level up, while others can be purchased either with the in-game currency, Costume Coins, or Microsoft Points, and this surely sets a new record for day-one DLC with over 100 items on the Marketplace.
What you actually get with your 1200 MSP download, however, is rather more slender, with just five maps and three gametypes. There's the self-explanatory Team Deathmatch; Fumigation, which shares more than a suffix with Call Of Duty's Domination; and Psych Warfare, a suitably madcap take on capture the flag in which securing and retaining a battery strips your enemies of their weaponry and reduces them to slapping. A free map is due next month, and we're confident this meagre launch offering will be further boosted over time, albeit for a fee.
If that sounds cynical, it's an assumption based firmly in fact: Gotham City Impostors has perhaps the most glacial unlock system of any shooter on the market. While you're granted a single unlock each time you rank up, it's always of one specific type; a weapon, or gadget, or perk, here called Fun Facts for no apparent reason beyond the desire not to call them perks. Make a bad decision, and you're stuck with it for hours. When you're first given a custom class slot, more than half of it remains locked, and you'll be several hours into the game before you have an entire loadout of your own design. You can, of course, pay your way past it, swapping Microsoft Points for unlocks or XP boosts. Suddenly you realise that the titular impostors aren't the wannabe superheroes or villains; this is a freemium game, masquerading as a paid download.
Xbox 360 version tested.