Seriously? You really don't recall much about the game... besides shooting stuff, all you do is this:And it had already nailed the atmosphere, a very important aspect in that type of game.
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The game's failure has nothing to do with bugs. Hellgate: London is just a series of repetitive randomly generated corridors filled with mindless enemies, occasionally interrupted by one of these shitty hubs, that are just NPCs in a circle giving you boring quests. And all hubs look the fucking same, they are all subway stations. More even, gameplay is basically "hold trigger button & strafe", especially since there's no ammo! You never have to reload, manage resources or anything, just equip highest DPS weapon and hold trigger button. Not to mention how bad the gunplay feels, since weapons have no impact whatsoever, and all feel the same.
Borderlands took the exact same formula, but with open-world and real weight behind the weapons. But their real jackpot was the tone, as the humour & cartoony characters give some flavur to the MMO-ish quests. Hellgate starts the game by dropping you in a alley and asking you to follow a guy you don't care and save teh world. Borderlands gives you a talking robot making jokes and task you to repair a vehicle so you can derp around and run over stuff.