The game of chomp is an example of a game with very simple rules, but no known winning strategy in general.
I copy the rules from Ivars Peterson's page http://www.maa.org/mathland/mathtrek_03_24_03.html
"Chomp starts with a rectangular array of counters arranged neatly in rows and columns. A move consists of selecting any counter, then removing that counter along with all the counters above and to the right of it. In effect, the player takes a rectangular or square "bite" out of the array—just as if the array were a rectangular, segmented chocolate bar. Two players take turns removing counters. The loser is the one forced to take the last "poisoned" counter in the lower left corner."
A nice non-constructive argument shows that the first player has a winning strategy. The winning strategy can be made explicit in very specific cases. As far as I know, the more general setting for which the winning strategy is known is when we have 3 rows and any number of columns, see http://www.math.rutgers.edu/~zeilberg/mamarim/mamarimhtml/chomp.html
My question is
Are there any recent advances on chomp?