There were so many big name games last year but the sales for them really weren't that great.

DmC didn't sell well.

Dead Space 3 sold considerably less than the others, probably won't be any more of those now.

Sly Cooper 4 had terrible sales.

Crysis 3 sold a lot less than the second one.

Metal Gear Rising only sold about 1 million or so copies.

Tomb Raider should have sold a lot better than it did.

God of War Ascension sold laughably badly, just over a third of GOW3 despite a much bigger userbase.

Gears of War Judgement not even a quarter of GoW3.

Bioshock Inifnite's sales are the weakest of the three despite the universal acclaim it got last year.

Dead Island Riptide sold like crap.

Remember Me sold like 400,000 copies.

Saints Row IV isn't really doing that great.

Splinter Cell has sold really poorly.

Batman Origins isn't doing anywhere as well as City.

Gran Tursimo 6 is doing terribly compared to GT5.

Ratchet and Clank sold poorly.

Killzone Mercenary sold poorly despite it being the Vita's big game that year.

Beyond also sold a fraction of Heavy Rain.

Then even big games like COD, Battlefield, Fifa, Assassins Creed all had games this year and aren't doing aswell.

Now I know they've been out about a year or less and they will be reasons for some of the games but this is a huge amount of games here that should have sold A LOT more than they ended up. I'm probably even forgetting a ton.

The gaming industry is dying slowly. Wait a couple of years and we will be playing on the streets with our friends!

Because the xbox 360 and PS3 suffered from the announcement of their next gen systems. When people saw the release date and the product themselves, they became devoid of current gen stuff. Also the MSRP for both consoles are still expensive for this late in the generation.

Particulars for certain games aside, I think it's safe to assume that many of the more dedicated gamers who usually buy the most were saving their money last year for next gen consoles.

Tomb Raider sold amazing.
Rising was niche and sold fine
No one wanted GOW:A & GOW:J
Dead Island was a glorified DLC and people weren't being tricked this time.
Remember Me had no advertising
GT6 released RIGHT around the PS4 and was a copy+ paste of GT5

The others were due to the launch of next-gen. I only have so much funds and chose to allocate them to purchase a PS4

There is obviously a video game crash  coming very soon.

Too many games on the market and not enough disposable income.

Because most of those games were poor.

Lots of different reasons.

Most of the annual games have been going for a long time and people are getting bored of them.

Games like GoW, Metal Gear Rising and Gears were spin offs and were never going to sell as much as the main series.

Sly Cooper is an old IP and a platformer, and aside from Mario those kinds of games never sell as much as they used to.

Some games, like Dead Island Riptide and Crysis 3 don't deserve high sales because they are not very good.

The other games you listed are concerning though, games like Tomb Raider and especially Bioshock deserved to sell more, but there are only so many 'hardcore' gamers around, and clearly not enough to sustain as many AAA titles as are being released.

cus you didnt buy them