Resistance: Fall of Man and Resistance 2 are both good choices if you like FPS.The latter of the two includes an 8 player co-op mode, which is actually still fairly active.

Folklore is an interesting one that's well worth taking a look at too.

I would also recommend picking up Ninja Gaiden Sigma. Great fun if you're looking for game offering a solid challenge.

The Atelier series is worth a look. The process of collecting items whilst exploring, then using those as ingredients to create new ones is the main focus of those games.

Ace Combat: Assault Horizon comes to mind right away. The introduction of the DFM mechanic left a lot of long-time AC fans very unhappy. While I did prefer the gameplay style found in the previous games of the series, it wasn't the new mechanic that had me left me dissatisfied with the overall expierience. My issue was with the short length of the campaign. I had been expecting a longer one (and a better story to go alongside it), given that the AC games had traditionally always placed an emphasis on the single-player expierience.

I didn't think AH was neccessarily a bad game as such. In fact it's a relatively enjoyable game in its own right, but it wasn't exactly the next AC game I had been looking forward to after the release of AC6 and Joint Assault.

A typical playthrough adds up to about 20 hours in length, from what I've heard. A game that I can play by myself and invest a good amount of time in was something I had been searching for (leaving aside my backlog of unfished/unopened RPG's that is). I think XCOM fits that description perfectly.

It's definitely on my list of games to buy. I'll probably get my copy tomorrow.

"Like a Phoenix Rising" from Ace Combat: Assault Horizon Legacy (or 'Ace Combat 3D: Cross Rumble', as it's known in Japan).

Ace Combat

Armored Core

Soul Calibur

Colony Wars

Fate (as in 'Fate/stay night')

Just SP for me. What little time I did spend playing with others when I ran a Gold account was spent playing co-op with a few friends.

Metal Slug 3 would go at the top of my list, then followed by the original Metal Slug and then '6.