Something like Liar Game or Death Note where the reader must constantly be in toes, the manga gives the reader the chance to "guess" the solution, that really ticks off your problem-solving skills. sort of like a mystery manga.

I think that Monster and 20th Century Boys may be like this. They are a bit different than Death Note and Liar game (which focus mostly on planning, deducting etc). I wanted to write more, but I guess it's not something you can explain, you have to read it (if you haven't yet)

Gamble Fish -- basically Liar Game on crack and steroids with probably a few tequilas to wash it all down.
Bloody Monday -- I've only read about 20 chapters, but it seems pretty psychological
Kurosagi -- This is also like Liar Game, except it's not a game and it's kind of less exciting
Spiral: Suiri no Kizuna -- I actually don't really remember what this is about but it probably works

EDIT: also Akagi

Last edited by magical_poof at 6:29 pm, Jun 30 2010

Himitsu
Gambling Emperor Legend Zero
Kaiji - Sort of
Pluto
Detective School Q - Sort of childish, though.
I second Spiral: Suiri no Kizuna - it fits your requirements well. Monster is pretty good, too.

Last edited by calstine at 9:00 pm, Jun 30 2010