When something's good, you obviously want it to last. It's human nature. That universal truth carries over into the world of videogames in the form of countless sequels to successful franchises. It's no mystery why there are a billion Pokemon games or 16 Metal Gears - we want these prime examples of gaming bliss to carry on forever. What we can't figure out is why some franchises lurch onward despite near-unanimous panning and bountiful negative press. These series get regular installments with little to no change from the previous game, sell their meager numbers and then descend upon us once again a year later with another ho-hum, stagnant title.

These are the games that should not be selling, or at the very least, should have stopped selling a long time ago. There's a decent answer for every single one of these games, though, and it's a little thing called money. These games sell just enough to justify another one. But why? We asked it in the strapline, but we're gonna ask it again: who's buying this crap?

Above: Guess what's not as fun as it looks?

7 - Armored Core
Number of games in series - 13
Average score from Metacritic - 6.8

Now here's a formula that just shouldn't fail - building-sized robots blasting each other straight into the big junkyard in the sky. The catch is that Armored Core has decided to place just as much gameplay emphasis on pre-mission mech customization as it does on in-game action. For every five minute sortie you take on (usually against some evil corporation or something to that effect), you'll spend twice as long memorizing what the hell an Exceed Orbit pod is or how much weight your mech can carry or whether or not these guns make you look fat. Cripes man, if we wanted to build the damn things we'd go do it ourselves. Just show us how to throw on some neon trim and a mini-fridge and we're there.

Still, the series has a small but devoted fan base. Fine. Different strokes and all that, we get it. But they've been playing the same thing since 1997 and only the hardest of hardcore fans could tell you the difference between one game and the next. The changes are so minute that they should be microtransactions by now. Serious modifications that need to happen, like better controls, also come in excruciatingly slow increments, so we'll all be 50 years old by the time developer From Software gets it totally right.

But there are 13 of these things already out there with more undoubtedly on the way. We know the Core fans will be there on day one, but could they please ask for more than what the developers are content to give? We want to like this series, but forgive us if we don't want to read an owner's manual before pressing Start.