DmC didn't sell well. 

The game was good but that didn't matter, the fanbase was furious at twilight Dante.

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

Apparently not that a good game and it deviated too much from its survival horror roots.

Sly Cooper 4 had terrible sales.

A decent game but quietly releasing it 8 years after its predecessor was dumb.

Crysis 3 sold a lot less than the second one.

Crysis 2 sold purely because it was the first CryEngine game on consoles and people were hped for it's visuals, it was rubbish and Crysis 3 is even worse.

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

A gimmicky hack 'n slash game, was well-received and did 1m+ on PS3 alone which is good enough.

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

It sold amazingly well, deserves more but selling over 4m in less than a year is great.

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

Do you realise how small the genre is? Apparently it has sold 2.7m which is great for a spin-off multiplayer prequel that's still not even a year old, DMC4 (the biggest game in the genre outside GoW) sold 2.9m on PS3 + 360 and that released in 2008...  Also Halo 4, a sequel, sold a lot less than Halo 3 despite a much bigger userbase, it happens.

Gears of War Judgement not even a quarter of GoW3.

This game was the epitome of mediocre and deserved to flop. Hope the next one is a return to form.

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

I'm pretty sure if you aligned the sales of the three Bioshock games on PS3 + 360 Bioshock Infinite is comfortably in the lead, still deseres better though.

Dead Island Riptide sold like crap.

Yeah, this game wasn't good.

Remember Me sold like 400,000 copies.

Looks like a decent enough game, queit release a week before The Last of Us just killed it.

Saints Row IV isn't really doing that great.

Probably blame Grand Theft Auto V for that.

Splinter Cell has sold really poorly.

This one was well-received but released to little fanfare, on PS3 + 360 it should at least outsell Splinter Cell: Conviction. The series really lost it's spark and I hope the next one is more like Chaos Theory.

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

This is because it's apparently nowhere near as good a game, also spin-off/prequel and less people want those. Although its sales still seem pretty good actually.

Gran Tursimo 6 is doing terribly compared to GT5.

A copy & paste of GT5 with just more content, releasing so soon after the PS4 killed any hype for it. Should still go on to sell a respectable amount.

Ratchet and Clank sold poorly.

Not been doing well for a while now, the game wasn't as good as ToD & AciT and the series seems to be on the decline.

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

The game isn't as good as people were hoping it would be and the Vita's lack of popularity ensured it wouldn't do well. 

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

The console generation transition affected all of them.

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.

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

DmC didn't sell well.  Wasn't a very good game.

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

Sly Cooper 4 had terrible sales.

Crysis 3 sold a lot less than the second one.  Was not as good as the 2nd game.

Metal Gear Rising only sold about 1 million or so copies.  Was an offshoot from regular series.

Tomb Raider should have sold a lot better than it did.  Sold OK.  Publisher overestimated what it would sell.  Great game though.

God of War Ascension sold laughably badly, just over a third of GOW3 despite a much bigger userbase.  Wasn't a very good game.

Gears of War Judgement not even a quarter of GoW3.  Wasn't a very good game.

Bioshock Inifnite's sales are the weakest of the three despite the universal acclaim it got last year.  Not quite as good as the original.  Number 2 which is easily the worst only sold off the original's hype.

Dead Island Riptide sold like crap.  Would have sold better if released as DLC.  Have to be honest I loved both DI games and bought this opening day.  The "tower defense" sections were great.  Easily the coolest looking steelbook I have ever owned and it came free for pre ordering.

Remember Me sold like 400,000 copies. Wasn't a very good game.

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.  Not even close to as good as City.

Gran Tursimo 6 is doing terribly compared to GT5.  I think people are hoping this would get PS4 release...

Ratchet and Clank sold poorly.

Killzone Mercenary sold poorly despite it being the Vita's big game that year.  Sold bad because it is on Vita.  Incredibly good game.

Then even big games like COD, Battlefield, Fifa, Assassins Creed all had games this year and aren't doing aswell.  The annual games all did poorly because of new gen announcement.  AC4 on PS4 is my favorite game of 2013.

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.