Dissidia: Final Fantasy. While I also recently started the excellent Batman: Arkham Asylum, I continuously fire up the PSP to get battles on Dissidia in. The Final Fantasy name in the title might have roped me in enough to give the game a try but the multiple layers of interesting game systems and rewards are what keep me coming back.
In a nutshell, Dissidia rewards you for almost every minute you spend playing it. Win or lose, you gain experience and one of the multiple forms of currency. You gain items for destroying parts of the stage, experience is awarded depending on how much damage you do per hit, and additional items are dropped for performing specific types of actions. There are also scheduled rewards for turning the game on each day and checking the calendar. Some days confer additional bonuses in the form of shopping currency multipliers, unlockable currency, experience boosts, or skill boosts. In addition, you can increase your chances of earning rewards even further by putting on specific pieces of equipment. Finally, there are multiple game modes that behave very differently but each add additional layers of rewards for completing battles in specific ways or minimizing the number of moves it takes you to reach the end of a map.
There are a total of 151 accomplishments similar in nature to achievements in an Xbox 360 game. One interesting thing about these accomplishments is the fact that almost all of them remain secret until you meet certain criteria. Once the accomplishment is revealed, you are usually only about halfway there but you can see your progress towards the goal down to fractional percentage increases. In addition, when new accomplishments open up, the post battle summary lets you know to check on your progress.
Add to all of this the fact that you have 12 characters with unique storylines along with 10 villains that do not, but which can be powered up and used in other forms of battle, unlockable art, music, movie, and Final Fantasy museum galleries, and a highly polished presentation and you have the formula for a game that will keep me busy for a long time to come. Normally in a situation like this I will go deep before I finish the game for the first time, but this year I am trying to increase the number of games I play to completion, so I wil be doing a lot of the bonus content after my first full playthrough.
While it might be easy to dismiss all of the rewards as the equivalent of a spigot of neverending candy that keeps you from focusing on the weaker aspects of the game including its somewhat ridiculous story, the unoptimized controls, or the lack of tactical depth in moment to moment combat, this game is very forward thinking in terms of how it keeps player engagement high enough to incentivize at least a single full playthrough. If you go though achievment completion statistics, even for high quality games like Half-Life 2, what you notice is that the number of people who finish a game is a small fraction of the total people who start it. One of the challenges we all face as developers is keeping players interested in our games, and I find it encouraging to discover a game that attempts to tackle this challenge head on in an interesting way.