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A primer on strategies

DNJ Dilemma comes with four built-in game strategies written by the game's author Paul Stephens, and we're challenging you to write your own to beat them!). 

Here are brief biographies of the built-in strategies:

Tit-for-Tat. This is a 'nice' strategy, in that it basically wants to cooperate. However it doesn't like being messed around. Tit-for-Tat will always play cooperate, unless you played defect in the previous round, in which case it automatically plays defect. Tit for Tat was allegedly the basis for the policy of 'Mutually Assured Destruction' adopted by the nuclear superpowers during the Cold War.

Suspicious Tit-for-Tat. This is like Tit-for-Tat, except that it always defects on the first round because it suspects that you might have done the same. Why can't there be more trust in the world - and thank goodness those nuclear superpowers didn't adopt this one instead!

Random defects. This one's a bit crazy - it just plays defect at random, taking no notice of what you've played in previous rounds. What's more, its percentage likelihood to defect changes with each game. A loose cannon that really forces you to adapt to its style!

Adaptive defects. The intellectual of the bunch, this one monitors your previous rounds and adapts its strategy accordingly, using special deductive algorithms (OK, they're really just my best-guess attempts at reading your strategy!) TIP - it's basically a 'nice' strategy, and recognises that someone who misbehaved a long time ago can have changed for the better recently. 

When you're playing DNJ Dilemma against an auto-selected strategy, the game doesn't tell you which strategy it's using until the game is over. This is the 'grown up' way to play the game - after all, if you were playing against a human opponent, they probably wouldn't tell you their strategy either! Manually selecting a strategy for the right-hand player allows you to practice your skills against the various opponents.

Tips on strategy. 
The ultimate zero-sum strategy is to defect every time ('Always Defect'). This will always get you a win over Tit-for-Tat, since Tit-for-Tat always plays cooperate in the first round. It will also achieve a win over most random and adaptive strategies, since they will normally let their guard down at some point, play cooperate, and give you a top score. 

However you won't score many points overall, since only the most gullible or generous strategies will play cooperate against you very often.  Against an Always Defect strategy (represented in this game by Random Defects with a very high percentage-defects value), your only option is to always defect yourself - unless, that it, you're the ultra-altruistic type who's happy to see the overall wealth of the community increase through your opponent's ill-gotten gains (see 'Always Cooperate' below). 

If you really can 'turn the other cheek' like that, then you're a finer human being than most of us. On the other hand, if meeting Always Defect makes a defector out of you, you can reflect on how quickly our morals crumble when we're faced with implacable evil and the need to survive.  

The best personal non zero-sum game strategy - in fact the best strategy, according to The Selfish Gene - is Tit-for-Tat. This strategy is 'nice' and 'forgiving', so wants to cooperate and is willing to let bygones be bygones, generating lots of cooperation when it's treated fairly. However it's also unyielding in its insistence on striking back against defects, so opponents with any intelligence will soon learn not to mess around with it (TIP - don't, however, assume that the computer's strategies have much intelligence!).   

Against Tit-for-Tat - well, you don't really have much choice, do you? You can defect against it on the first round, but unless you let it have a cooperate-defect round back, you'll end up locked into a defect-defect sequence that will see both of you score very few points. 

That's OK if you're a die-hard zero-summer, but if you like actually seeing some digits on the scoreboard, your only real option is to play fair against it, pocket those nice cooperate-cooperate payouts, and not get envious of your opponent's points total. 

The ultimate community-oriented, non zero-sum strategy is Always Cooperate, in which you play co-operate whatever your opponent has done to you. It can generate high combined points scores, although this may be largely due to your opponent walking off with lots of juicy cooperate-defect scorelines! These won't be as high as when both players co-operate all the time, but at least you'll have done your bit! 

If you find yourself playing against Always Cooperate (represented in this game by Random Defects with a very low percentage-defects value), then you really do have a moral dilemma. You can reciprocate its honesty, pocket lots of nice cooperate-cooperate payouts, and watch the community's wealth grow as the combined scores go through the roof. Or you can take that sucker for everything it's got, bank those gorgeous defect-cooperate bonanzas, and leave the community to sort out its own problems. Which kind of player are you?